Keithley 196 Service manual

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Model 196

System DMM

instruction Manual

Contains Operating and Servicing Information

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and tiorkmanship for a period of 1 year from date of shipment.

Keithley Instruments, Inc. warrants the following items for90 days from the date of shipment: probes, cables, rechargeable batteries,

diskettes, and documentation.

During the warranty period, we will, at OUT option, either repair or replace any product that proves to be defective.~~ :

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Ct&e.land, Ohio. YOU will be given Prompt assistance and return instruciions. Send the product, transport&~ prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance of the original warranty period, or at least PO days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse of any product or part. This warranty also does not apply to fuses,~software, non-rechargeable batteries, damage from battery leakage,~or problems arising~55Zi-i ncmii~l wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTtiERWARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PRO\IIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, JNDIRECT, SPECIAL, INCIDENTALOR CONsE:QUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS JNSTRIJM.ENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED To: COSTS OFT REMOVAL

AND INSTALLATION, Lossm SUSTAINED As THE RESULT OF IN3URY TO ANY PERSON, OR DAMAGETO PROPERTY.

Model 196~ System DMM

Instruction Manual

01986, Keithley Instruments, Inc.

Test Instrumentation Group

Cleveland, Ohio, U.S.A.

Fourth PrintingJanuary 1992

Document Number: 196-901-01 Rev. 0

Safety Precautions

The following safety precautions should be observed befoE using this product and any associated inshvmentation. Although some instruments and accessories would normally be used with non-hazardousvoltages, therearesituatio~iis where hazardous conditions may be present

This product is intended for use by qualiied personnel who iecognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read the operating information carefully before using the product.

Exercise extreme caution when a shock hazard is present. Lethal voittige may be present on cable connector jacks or test f?xtures. The American National Standards Instih~te (ANSI) states that a shock hazard exists when voltage levels greater

than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring.

Before operating an inskutient, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.

For maximum safety, do not touch the product, test cables, or any other instruments while power is applied to the circuit under test. ALWAYS remove power from the entire test systern and discharge any capacitors before: connecting or disconnecting cables or jumpers, installing or removing switching cards, or making internal changes, such as installing or removing jumpers.

Do not touch any object that could provide a current path to the common side of the circuit under test or power lie (earth) ground. Always make measurements with dry hands while standing on a ~JY, insulated surface capable of withstanding the voltage being measured.

Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications and operating inform&ion, and a~ shown on the instrument or test fixture rear panel, or switchiig card.

Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance limited sources. NEVER cbnnect switching cards directly to AC tin. When connecting sources to switching cards, install $~~tive devices to lit fault current and voltage to the card.

When fuses are used in a product, replace with same type and rating for continued protection against fire hazard.

Chassis connections must only be used as shield connections for measuring circuits, NOT as safety earth ground connections.

If you are using a test fxtwe, keep the lid closed while power is applied to the device under test. Safe operation requires the u.s$of a lid interlock.

Ifa @saew ispresenton~hetest tixhm?,connectit tbsafety earth ground using #18 AWG or larger wire.

The $ symbol on an instrument or accessory indicates that 1oOOV or more may be present on the terminals. Refer to the product manual for detailed operahlng information.

Instrumentation and accessories should not be connected to humans.

Maintenance should be performed by qualified service personnel. Before perfo&ng any maintenance, disconnect the line cord~and all test cables.

DC~ VOLTS 6% Digits,

SPECIFICATIONS

ANALOG SETTLING TIME: <lm.s (<2ms on 300mV range), to 0.01%

of step change.

CMRR: >lZOdB at dc, MHz or 6OHz (iO.O5%) with lkQ in either lead.

NMRR: >M)dB at50Hz or60Hz (iO.0546). ~~

RESPONSE: Tiue root mean square, ac coupled. CREST FACTOR (ratio of peak to rms)z Up to 3:l allowable. NONSINUSOIDAL INPUTS: For fundamental frequencies < -, mest

factor ~3, add 0.25% of reading to specified accuracy for 3oomV and 3V ranges; add 0.6% of reading to specified accuracy for 30V and 3fXlV

ranges. INPUT IMPEDANCE: lMlI shunted bv <12OoF. 3dBBANDWIDTHz 3WkHzfypical. ’ ’ MAXIMUM ALLOWABLE INPUT: 3oOV -, 425” peak, 10’ VHz,

whichever is less. SETTLING TIME: 1 second to within 0.1% of change in reading.

LINEARI’IY Linearity is defined as the timurn deviation from a straight

line between the readings at zero and full range: 1Oppm of range for

~3V-3ooV ranges; 15ppm of range for 3OOmV range; at 23OC il°C.

MAXIMUM ALLOWABLE INPUT: 300V rms. 425” peak, whichever is

less.

TBMF’ERATURE COEFFICI@‘JT (0=18”C & 28Y?,*C):

< i(O.l x app!icable accuracy specification)K below 2OkHz,

f(0.2.x) for 2okHz to 1ook?iz.

CMRR: >6OdB at 5OHz or 6OHz (*0.05%) with IkR in either lead.

dB (Ref. = 1”):

INPUT *OHa-~0gz

.4CC”RAcY *a

1 Year, IP-WC

?OW-?c!

-. P??LUnoN

WNETGURATION: Automatic 2- or&,ire. Offset compensationavai!ab~e OBN CIRCUIT VOLTAGE: 5.5V maxinwm.

on 3wiXOkO ranges, requires proper zeroing. Allowable compensation of ilOmV on 3OilQ range and ilWmV on 3ktl and 3OkO ranges.

MAX, ALLOWABLE INPIJZ 3wV rms, 425V peak, whichever is less.

JJNEARIlY Linetity is defined as the madmum deviation from a &might

line between the readings at zero and full range: 20ppm of range for SCO@3OkO ranges, at 23°C iYC.

3mA

3iE

3 A

‘4wigit count error is 20. 3K-digit CO”“t error is 5.

MAXIMUMALLOWABLHINPUT: 3A, 250”. OVERLOAD PROTECTION: 3A fuse (25OV), accessible from reii~ panel. TEMPERATURE COEFFICIENT (O”-18’C & 2S”-500C):

c iCO.1 x applicable accumw svecification)PC.

1 For Sinewave inputs >x.m EOuntS. For 4Vdigit accuracy, divide cou*t error by

10. .%3lidigit accuracy, count errOI b 5. Jn 3vl- and 4K.digit modes, specificati‘J”d apply for stnew.we inputs ,200Hz.

RESPONSE: True mot mean square, ac coupled. CREST FACTOR (ratio of peak to rms): Up to 3:l allowable at % full scale. NONSINUSOIDAL INPUTS: Spe&d accwacy for fundamental fquen-

ctes <lkJ&, CI& factor <3. SEmING TIME: 1 second to within 0.1% of change in reading. MAXIMUM ALLOWABLE INPUT: 3A, 250V. OVERLOAD PROTECTION: 3A fuse (UOV) accessibl&fiom rear panel.

TEMPERATURE COEFFICIENT (O’-18’C & 28%d”Qi~ ~’

< f(O.l x applicable accuracy specification)i°C.

dB (Ref. = ImA): ‘4CC”RAcY *a

INPUT

-34 to +69 dB (ZOJ4.4 to 3.4) 0.2 0.01 dB

-54 to -34 dB

@!A to 20PA)

10 n.4 0.05 + 10

1ooP.A

10 K.4 0.09 + 10

1 Year, 1S%B’C

2oH51okHz

0.05 0.05 + +~ 10 10

0.9 0.01 dB

* v

~~~

RE8OLuTION ~~~~

tiAXIMUM READING RAT&

DCV, DCA, ACV, ACA READINGS/SECOND

conttn”ovs into Extemal Rigger into Triggered via

Internal Buffer I”temd Buffer

IEEE488 Bus

IEEE-488 BUS IMPLEMENTATION

MULTILINE COMMANDS: DCL, LLO, SDC, GET, GTL; UNT, UNL,

.~- SPE, SPD.

UNILINE COMMANDS: IFC, REN,~EOI, SKQ, ATN.

INTERFACE FUNCTIONS: SHl. AHl, T6, TBO, L4, LEO, SRl, RLl, ?PO,

DCI. DTl, CO, El.

PROGRAMMABLE PARAMETERS: Range, Function, zero, Integration

Period, Filter. EOI. Trigger, Terminator, Delay, ?OO-Reading storage, Calibration. Display, Multiplex, Status, Service Request, Self Test, Output Format. TRANSLATOR.

GENERAL

RANGING: Manual or autoranging. MAXIMUM READING: 3029999 counts in 6%.digit mode. ZERO: Control subtract: on-scale value from subseqtient readings or allows

value to be prog&nmed.

CONNECTORS: Analog: Switch selectable front or rear, safety j&s.

Digital: TRIGGER input tid VOLTMETER COMPLETE &put on iear

panel, BNCs. WARMUP: 2 hours to rated accuracy. DISPLAY: 10, 0.5-in. alphanumeric LED digits with decimal point and

polarity. Function and IEEE-488 bus status also indicated.

ISOLATION: Input Lo to IEEE Lo orpower line ground: 5oOVpeak. 5~xlC+

max. VI+ product. >lO’D paralleled by 4OOpF.

DATA MEMORY: 1 to 500 locations, programmable. Measurement inter-

vals selectable from lms to 999999,&s or triggered.

BENCH READING RATE: 5 readings/second (2lsecond on 30M8 and

3COMtl ranges).

FILTER: Weighted average (exponential). Programmable weighting, 1 to

l/99.

OPERATING ENVIRONMENT: O”-500$ 0%.80% relative humidity up

to 35T; linearly derate 3% RH/“C, 35’C-5Ci’C (0%.60% RH up to 28OC

on 3oOMB range).

STORAGE ENVIRONMENT: -25” to +65OC. POWER: 105.125V or 210.UOV, rex panel switch selected, 5OHz or 6OHz,

30VA max. YO-1lOV and 18022OV versions available upon request.

DIMENSIONS, WEIGHT: l27mm high x 216mm wide x 359mm deep

(5 in. x 8% in. x 14% in.). Net weight 3.7kg (8 Ibs.).

ACCBSSORIES AVAILABLE:

Model lOlYA-1: 5%.in. Single Fixed Rack Mounting Kit Model lOlYA-2: 5’%-in. Dual Fixed Rack Mounting Kit Model 10195-1: 5’%-in. Single Slide Rack Mounting Kit Model 10195-2: 5X-b,. Dual Slide Rack Mounting Kit Model 1651: 5&Ampere Shunt Model 1681: Model 168s RFPmbe Model 1685: Model 1751: Model 1754: Model 5806: Model 7W7-I: Shielded IEEE-488 Cable, lm Model 7007-2: Shielded IEEE-488 Cable, 20, Model 7008.3: IEEE-488 Cable, 3 ft. (O.Ym) Model 7008-6: IEEE488 Cable, 6 ft. (1.8m)

Prices and specifications Subject to change without notice.

Clip-On Test Lead Set

Clamp-On Current Pmbe General Purpose Test Leads Universal Test Lead Kit Kelvin clip Leads

TABLE OF CONTENT!3

SECTION l-GENERAL INFORMATION

1.1

1.2

1.3

1.4

1.5~ :p7

1.8

1.9

1.10

INTRODUCTION. ...........................................................................

FEAI-URES ...... .;. ................

WARRANTY INFORMATION .................................................................

MANUAL ADDENDA ..........

SAFETY SYMBOLS AND TFRMS SPECIFICATIONS

INSPECTION ..............................................

USING THE MODEL 196 MANUAL

GE’JTMG STARED .............................

ACCESSORIES .................... .~: .~.~;~.~..~;~..~~.~;-;;~.‘;~.~. .~;~; ;:~.~.

............................................................................

;~:~.~ .... .;.e:.;. .. .;. .......................................

; ..............................................................

............................................................... l-l

SECTION 2-BASIC DMM OPERATIONS

2.1

2.2

2.2.1

2.2.2

2.2.3

2.2.4

2.3

23.1

2.3.2

2.33~

2.3.4

2.4

2.4.1

2.4.2

2.4.3

2.5

2.6

2.6.1

2.6.2

2.6.3

2.6.4

2.65

2.6;6

2.6.7

2.68

2.6.9

2.6.10

2.6.u.

2.7

27.1

2.7.2

2.7.3

2.%4

2.75

2.7.6

2.7.7

2.7.8

2.7.9

INTRODUCTION ...........................................................................

POWER UP PROCEDURES .........

Line rower ...................................................

Power-Up sequence. Factory Default Conditions

User Programmed Conditions .................................................................

FRONT PANEL FAMILIARIZATION

DisplayandIndicators

controls..

~1nputTermine.k

Calibration Enable Switch

REAR PANEL FAMILIARIZATION

Controls Connectors and Terminals

Fuses.. ERROR DISPLAY MESSAGES. ..~.;Z:..; BASIC MEASUREMENTS

WarmUpPeriod

Zero.........................~............~.~.......~

Filter

DCVolta eMeasurements..

.Low-Leve Measurement Coiisiderations

Resistan& Measurements ...................................................................

TRMS ACVoltageMeasurements Current Measurements (DC or TRMS~~AC)

dBMeasurements

:TRMS Considerations

~~dBApplications .......................

FRONT PANEL PROGRAMS

Program 0 (Menu) Program2(Resolution) Program4(MX+B)~.

Program5~/LO/Pass).....................;

Program 6 (Multiplexer, Auto/CAL)

Program30(Save)..................~.....~

Program 31 (IEEE Address).

Program 32 (Lie Frequency) .......................................................

Program 33 (Diagnostic).

........................................................................................

................................................................................... 2-5

.....

_. ....... .

.......................................................................................

............................................................................

......................................................................

.............................................................................

...................................................................

....................................................................

.............................................................................

.....................................................................

...........................................................................

.........................................................................

...................................................................... 2-15

........................................................................

....................................................................

........................................................................... 2-18

.....................................................................

_._.~ .............................. ..I..

.................................................................

....................................................... __

...

~.~~..~...=_

...........................................................

................................................................... 2-17

.......................................................................... ~2-21

l-1 ..

.~.-.~:.: l-l

l-1 l-l

l-2

....

l-2

2-l 2-1

2-l 2-l

2-2 2-2

2-2 2-4 2-4 2-5

2-5 Z-6

2-6

2-7

2-8 2-9 ~~~

2-11 2-12 2-13 2-13

2-17 2-18

2-18

2-20

2-22

. ....................................

.......................................................... l-2

.; .........................

.... : .... .;~;;

: .................................

.......................................................... 2-2

.....................

......................................... 2-7

.................

..................................................... 2-10

.... ;. ........... .I ...............................

................

.............................................. 2-19

..........................................................

.................................................. 2-20

~...~;. ... .

..: . ..*-.

..........

:.~

....................... .~.

..~~...._~. ..~..: .. .;. ....... 1-2

.~~.-.: . :~.-;~; : .~: ;~. ........ l-3

....................... 2-l

...... ........

.;...:~;.=;

:..~: .............. .

_. ........... 2-21

;~~;~;::~ 2-6.

........

2.7.10

2.7.11

2.%x?

27.13

2.7.14

2.7.15

2.7.16

2.7x7

2.8

2.8.1

2.8.2

2.9

2.9.1

2.9.2

2.9.3

Program 34 (MX+B Pammeters) ............................................

Program 35 (HI/LO Limits) ..............................

Program36(Calibration) ...................................................................

mgram 37 (Reset) ..................

Programn ................................................................................

Program ZERO.. .............. .: .~;:.~.~.

Program FILTER

................. ..~.._~~

Program dB .................................

FRONT PANEL TRIGGERING .................................................................

One-ShotTrigge~ring.. ........ I.~...;..~

Triggering Readings Into Data Store.

EXTEEWAL TRIGGERING ...........................................

ExternalTrigger.. ..........................................................................

Voltmeter Complete ...................

~Trigering Example..

......................................................................

SECTION 3-IEEE-488 PROGRAMMING

., ..... _~. ... _ _ .... 2-22

., ...... ., ............................

., .... __. ................. -. ............................

.............................. .I. ..

. ... I~.~:.-. .......... .l~. 2-24

................................................... .._. 2-24

_,_,_ ............................................

.................. .;..... T . ..I. .............................

..................... ., .... __ .............................

., .. Z-25

_. ........................

.~._ .. .._. ............. ___~. ........................

._ .... 2-26

2-22 2-23 2-23 2-24

2-25 2-25 2-25

2-26 2-26

2-27

3.1

3.2

3.3

3.4

3.5 ~~~,

3.6

3.6.1

3.6.2

3.7

3.7.1

3.%2

3.8

3.8.1

3.8.2

3.8.3

3.8.4

3.8.5

3.8.6

3.8.7

3.8.8

3.9 ~

3.9.1

3.9.2

3.9.3~

3.9.4

3.9.5

3.9.6

3.9.7

3.9.8

3.9.9

3.9.10

3.9.11

3.9.32

3.9.13

3.9.14

3.9.15

3.9.16

3.9.17

3.9.18

INTRODUCTION.. ........................................................

A SHORTCUT TO IEEE-488 OPERATION BUS CONNECTIONS..

...................

........................................................ 3-l

. . ..~.~_~..~_ ............................................

INTERFACE FUNCTION CODES ..............................................................

PRJMARY ADDRESS SELECTION ......................................

CONTROLLER PRO%

RAMMING

........ _.

................................................... ~3-6

Controller Handler Softwae ..................................................................

BASIC Interface Programming Statements.

FRONT PANEL ASPECTS OF IEEE-488 OPERATION

FrontPanelErrorMessages.. ... ~;.;~.~..:...:~~ ...

IEEE-488 Status Indicators and LOCAL Key

GENERAL BUS COMMAND PROGRAMMIN

....................................................

..........................................

. ....................... ~..~..~...~;.~ ..............

....................................

G ................................................

REN (Remote Enable) .....................................................................

IFC (Tnterface Clear) .......................

__ _., .............................................

LLO (LocalLockout).......................................................~

GTL(GoToLocal). ........................................................................

DCL(Devi?e Clear) ........................................................................

~SDC t Selective De& Clear), ..................

1. _.~. .... -. ........... ._ ..........................

GET Group Execute Trigger) ..................................

Se&d Polling (SPE,SPD). .1.. ................

DEVICE-DEPENDENT COMMAND PRWWNG

Execute(x).

Fur&on (F) ................

Range(R). ......................

................................................. .._.

;

..............................................................

.._ ......................................................

.-;. ........ .: ....................................

............................. _..:. . ;,

zero(Z). .........................................................

Filter(P).......................~~............................................................3-

Rate (S).

........

......................................................................... 3-19

.;.

Trigger Mode Q ............................................................................

Reading Mode (B) .............................

Data Store Interval (Q) and Size (I) Value (V) and Calibration (C)

...............................................................

..........................................................

__ ..........................................

Default Conditions (L) ..............................................................

DataFormat(G). .... .

............. ;~:.

SRQ Mask (M) and Serial Poll Byte Format

...............

:I;.....; .:.

..................................................

EOI and Bus Hold-off Modes (K) ................................................................

Terminator(Y) .............. ~..~..~...~...l~.~ _.

........ _ ..........................................

status (u) ...................................................................................

Auto/Cal Multiplex (A). Delay (W)

.................................................................................... 331

....................................................................

...................

_ ........... _ ......... 3-6

__ __ ,3-7

.~I. .... ._ ....... 3-10

................ 3-11

-~.~. ........

t. ................. 3-n

....

........................... 3-17

..- .......................

.~: .... : 3-23

........................ 3-23

3-l

3-4 3-5

3-7 3-7

. 57

3-n

., . 3-ll

3Xl

3-12 3-12 3-13

3-13 3-14

3-17 3-18

3-18

3-20 3-20 3-20 3-22

3-24 3-26 :I!

3-29

3.9.19 ~Sem&~).

3.9.20

whit Button (H)

3.9.21 Display (D)

3.9.22

3.10

3.10.1

3.10.2

3.10.3

3.108

3.10.5

3.10.6

3.10.7

3.10.8

3.10.9

3.11

lntemalFilter(N) .........................................................................

TRANSLATOR SOFIWARE

Translator Format. WildCard($).

NEW and OLD ................. .;~,..~..~.~.

Combining Translator Words Combining Translator Words With Keithley IEEE-488 Commands Executing Translator Words and Keithley IEEE Commands

SAVE.. ..................... ~;~.~...~v ................................

~LIST

FORGET ............. :.I;

BUS DKC.4 TRANSMISSION TIMES

...................................................

...................................................................... ~...~.~.~__ .. 3-31

...............................................................................

..................................................

.............................................................

...............................................

..............

.........................

.......

_.~.

......

.._

.....................

..........................................................

SECTION 4-PERFORMANCE VERIFICATION

.._. . .._. . .- ................. 331

....

._.

.........

.......

_.,_~ ., . .,

. . c____. ... .._

.............. 335

....

...................... I. ... ,:~. ......................... 3-35~

..................

..............

................

.,_

..............................

....................................

.........................

1;:.

..........

.: ........................ 3-37

;.~.

;...;. 3-37

....

..~ ...................................

332 3-33

3-33

~3-34

3-35 3-36 3-36

3-37 3-37

...

4.1

4.2

4.3

4.4

4.5

4.5.1

4.5.2

4.5.3

4.5.4

4.5.5

INTRODUCTION ENVIRONMENTAL CONDITIONS

INITIAL CONDITIONS. ..... -

RECOMMENDEDTESTEQUIPMENT..

VERIFICAXION PROCEDURES.

DC Volts Verification ........................................ __ __ _._ ___ __

TRMS AC Volts Verification ......

Ohms Verification

DCCurrentVerification.. .... ;I;. ....... ;~ ................

TRMS AC Current Verification

..............................................................................

............................

_*_..._..__._ ................ ~.~_~. ................... ..--

.................................................................

..~.~......................~...I..~...........~.......~ ..........

.........

..~.._~:.

............

..............................

SECTION 5-PRINCIPLES OF OPERATION

5.1

5.2

5.3

5.3.1

5.3.2

5.3.3

5.3.4

5.4

5.5

5.6

5.61

5.6.2

5.7

INTRODUCTION OVERALL FUNCTIONAL DESCRIPTION ANALOG CIRCUITRY..

Input Signal Conditioning. Multiplexer

~+2.1V Reference Source ...........

Input Buffer Amplifier

A/D CONVERTER ...............

CONTROL CIRCUITRY DIGITAL CIRCUITRY

Microcomputer.

Display Circuitry ................

POWER SUPPLIES ....................

...........

.___ ~.~_~.~.~._.

............................................

....................

.................................................................................

.............

.........................................................

.._..~~.~_~_..................................~......_....._~ ...

.......................................................................

........................................................................................................................................................

..~._.......................~....................~ ...........

..................................

......

~.;;.

~...~.;~;.

...............

................................

.........

. ._

. .m .,._

.....

~_-_.

........................................................

...........................................................

. .......... _:~ ................. 5-l

.~.~.~~-. . .~; _.

................................

. .................... -. .... ~~~.~~:.~~. .................

..~.~...._..~ .............................................

......

...............

.........

......................

..... ;..~; ..:.

.~;~.~.-;.-;.......;. 4-4

......

................

...........

;

............

..-- ...

.~..;

...

....

41 4-1 41

41 42 4-2 4-2

4-3 4-5

5-l

5-4

5-7 .55

5-8 ;

5-9 5-9

SECTION B-MAINTENANCE

6.1

6.2

6.3

6.3.1

6.3.2

6.4

6.4.1

6.4.2

INTRODUCTION LINE VOITAGE SELECTION FUSE REPLACEMENT

Line Fuses CurrentFuse

CALIBRKION .....

RecommendedCalibrationEquipment Environmental Conditions.

..............................................................................

..................................................................................

....................... . ................

..................................................................

....................................................

..,

____.:

...

.......................

.........

.._....................~

..................

..~~.~...~..-*~~

. .._

__:.:

........

-;~

..................

I,;;...;..;;.~....;.~~~:

...................

.................................................................................

.~_.

6-l

....

6-l

2;;

iii

6.4.3

6.4.4

6.4.5

6.4.6

6.4.7

Warn-UpPeriod..

............

CALENABLE Switch.. .................

Front Panel Calibration ...............

IEEE-488Bus~CaIibration.. ..............

Calibration Sequence .... ! ........ ,.._._

DC V&s CaI’b 1 *alon.. t’ ............................

6.4.10

6.4.11

6.4.72

6.5

6.6

6.7

6.7.1

6.7.2

67.3

6.7.4

6.7.5

6.7.6

Resistance Calibration. .......... .I

TRMS~ACVtiltsCalibration.. ...................

DC Current Calibration .............

TRMS AC Currefit Calibration ................................................................

DISASSEMBLYINSi-RUCTIONS ..........

SPECIAL HANDLING OF STATIC-SENSI’?IVE DEVICES

TROUBLESHOOTING ............. .~I,~_.

Recommended Test Equipment .........

Power Up Self Test ..................

Program 33 - Self Diagnostic Program

Power Supplies ...................

Signal COnditioning Check .-. .. .:.:~~.

Digital and Display Circuitry Checks

SECTION 74iEPLACEABLE PAFITS

... I......,: ..:. .... ..:.~:..:...~ ..;

..I...

...........

........................................................

_.-.

.......................

......

.....

.......................................

.._. __.__ _...................,

.. :&.-. _. ...... ‘~-. ,_. ... .~_ .............................

.._ ..........................................

.... _, .......................................................

;~. .._ .. :.:~:.~ ... . ...............................

_. . __ ......... ... ._. .....................................

~...__._ . ,........I_ .......... ...............................

........

.................... .~:.

- ..l..: ..........

... ., .........................

-., .. ..I. ................ ._,_ _~. .,..__.

.-~- ._.~_._. .......... ._~.~.~.~.~.~.~. ., . ___.,

................ ._ ....... . _, ...............

.~.~_.__-. ..... .___“.,_. ............. _. .........................

....... .~-.:~. ....... _. ....... ._. ........................

........................................................

. ............. 6-3

6-3 6-3

.. ~.~6-4

__ . _ .. ,6,-4

6-5

6-6 6-7

., . 6-9

6-10 6-11

_I...~ ............ ~&lZ

: ......

., ... 6-12

...................... 6-14

. ., ...................... 6-14

__. ............. 6-14

6-15

_. .. 6-15

6-15

7.1 Z2 z3 %4

7.5

INTRODUCTION...~.~..~:~...;..;~..~.~..; .._.....I.... _......_......................_.._......_ _..

PARTS UST..............................................~....................~..~......-.... 7-1

ORDFRINGINFORMATION ..,................,. _.._ __........... ~-~ . . . . ~~.-- _..... ~-...1.~...~...-~~1~3~

FACTORY SERVICE . . . . . . . . ;..;.;....;...;;~-__.~.~-;; ._.. ~..__ . . . . . . . . . . . . . . I_ . . . . . . . . f . . . _ . . . . . . . . . . . .

SCHEMp;TIC DIAGRAMS ps;rrj: COMPG&T LOC&TIOti DRAWINGS . . . . : .~ .~. ; _ _ . . .~. __ . 7-l

APPENDIX A

ASCII CHARACTER CODES AND IEEE-488 MULTILINE INTERFACE COMMAND MESSAGES.. 1. A-1~

APPENDIX B

IBM PC/XT and MODEL 8573A PROGRAMMING . _ _. . . . . . _. . . _ _ _ _. _. . _ . _ __. . . k-1

APPENDIX C

CONTROLLER PROGRAMS. .‘, . .‘:. . ., . . . ::. .~. . __ . . . _ . .~. . . . _ . . . . . . , . . . . . :. . . _. .

APPENDIX D

IEEE-488 BUS OVERVIEW . . . . ._ . . . . . . . . . . . . . . . . _ . . . _ . , . _ . . _ __ _. . . _ . . . . . . _ . _ _.

7-1

;rl

C-l

D-l

LIST OF TABLES

SECTION 2-BASIC DMM OPERATION

2-l 2-2 23

Et 2-6 2-7 2-8

Factory Default Conditions ......

ErrorMessages ResistanceRanges..

Corresponding Voltage +ferenceJev$@for Impedance !7eference.

Comparison of Average and TRMS Meter Readings .............................................

FrontPanelPrograms..

Display Resolution ........................... .............

ExampleMX+BReadings.:.

.......... ..~.......;-.....................,......................;

............................

...... ~.:.

.~I. :. . : .;

.... . ..... :z.:. ... ~.:. ...

......

SECTION 3-IEEE-488 PROGRAMMING

3-l 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-ll 3-12

3-13 3-14 3-35 3-16

IEEE-488 Commands Used to Select Function and Range ........................................

~lEEE Contact Designation. ..............................

Model 196 Interface Function Codes ............................................

BASIC Statements Necessary to Send Bus Commands ...............................

FrontPanelIEEE488Messages.. General Bus Commands and Associated BASIC Statements ;~. FactoryDefaultConditiotis

Device-Dependent Command Summary ............................................

Range Co~andSummary...~..,,:. Rate Command Summary High Speed Data Store SRQ Command Parameters Bus Hold-off Ties

Translator Reserved Words and Chxacter ....................................

Translator Error Messages ... z

Trigger To Reading-Ready Times (DCV Funct&~n) ...............................................

........................................

..........................................................................

............................................

~~;I.~;.~~...;.;.~~; ....... ;;...~.J:.:..~..: ...

.......

..................................................

....................................................................

:~.

...

.................................................

. ............................................

.:~. ............... . .......

........

I...;

......................

:I............... l............

.....................

.z.:..~ .:. .................

.__

.... _ .............................

. ............. ~;;.;;~;;.

i ......................................

.................

:r:..~-..~.~ ~..~i: ..%.

._.

.......

. .... -..I~;~.~ 1..

..... ...........

... _ .. _ ................

.~.~.:.

......

.............. 2-6

.: ...... ;~. ..... 2-15

:.~. .......... 2-l7

... i...;;. 2-19~

...

........

1..

...........

..................

.~;.

...............

............ 3-12

..........

............

................

-.!L. 3-l$

......

3-22

__ 3-25

__ 3-26

3-33 3-34

3-37

2-2 2-12 2-16 2-18

3-3 35

3-6

3-7

3-8~

3-10 3-E 3-19

SECTION 4-PERFORMANCE VERIFICATION

4-2

22 45 46

RecommendedTest Equipment

Limits for DCV Volts Verification LimitsforTRMSACVoltsVerifibation..

Limits for Ohms Verification ... .:~. ;~.~.~. ....... ;...~

Limits for DC Current Verification

Limits for AC CurretifVerification

................................................................

........ .

.............................................................

.......................

SECTION 5-PRINCIPLES OF OPERATION

5-1

Input Buffer Amplifier (U35) Gain Co*gt&ation . . . . . . ‘. . . . . .‘; i . . . . ~ . . . . . _~. _ . _ . 5-7

.......

....................

.....................................

MY..;

....

t..

~.I;

......................

i-3

.:. ...................... 4-4

4-4

........

4-5

SECTION 6-MAINTENANCE

6-l 6-2 6-3 6-4 6-5 6-6

6-7 6-8

6-9 6-J.0 6-12 6-12 6-13 6-14

LineVoltage Selection LineFuseReplacement Current~Fuse Replacement Recommended Calibration Equipment

DCVoltsCalibration......................~.....-

ResistanceCalibration TRMS AC Volts Calibration. DC Current Calibration TRMS AC Currefit calibration Recommended Troubleshooting Equipment Model I.96 Troubleshooting Mode Power Stipply Checks. Digital Circuitry Checks. Display Circuitry Checks

............ ..L

.......................................................................

...................................

........................................................................

.................

............ .~.....................

.......................................

................................................

........................................................................

.....................

.........................................................

..........................................................

..............................................................

_. ....... __. ......................

..............................................

_, .. _._ ...............................................

.......................................

....................................................

., .. __ .............

_. ............................

.........................

_ ............ _

..... ., .. ., ., 6-18

6-l 6-2 6-2 6-2 6-5 6-6

6-7

6-10 6-11

6-14

6-15

6-18

6-19

SECTION 7-REPLACEABLE PAFKS

7-1 Display Board, Parts List.. . . . . . . . . . . , . . . . _ _ .-. .: . _ . _ :. . . . _:. . . . . _. . . . . . :. . . . .‘. . ._ _. 7-3

7-2

7-3 AnalogBoard,Parts List . . . . . . . . . . . . . . . . . . . . ..~.............................................. 719

7-4 Model196MiscellaneousParts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._........................

DigitalBoard,PartsList........................-~.............................................. 7-S

7-33

APPENDIX B

B-1 BASIC Statements Necessary to Send Btis

APPENDIX D

D-l lEEE488Bus Command So D-2 D-3 Typical Addressed Command Sequence.

;;

Hexadecimal and Decimal Command Codes Typical Device-Dependent Commiind Sequence

IBEE Co

mmaid

Group ................

............................................................

mmands........................................... B-1

...................................................

.......... D-7

.............................................

.. ;~. ...................

_ ..... ; ....................................

.; ..... . .. .;~..~ ............

., .......

D-3

D-7 D-7

., .... D-7

LIST OF ILLUSTRATIONS

SECTION 2-BASIC DMM OPERATION

2-l 2-2 2-3 2-4 2-5 2-6

2-7 2-8 2-9

2-10

Model196FrontPanel................................................~.......~.......~-

Model 196 Rear Panel

DCVoltageMeasurements ........................... ..~....~.....-...............~.-...~-

Two-Terminal Resistance Measurements Four-Terminal Resistance Measurements TRMSACVoltageMeasuremement Current Measurements. External Trigger Pulse Specifications Voltmeter Complete Pulse Specifications External Triggering Example

.............................................................

....................................................................................................................................

.........

SECTION 3-IEEE-466 PROGRAMMING

3-l 3-2

2 3-5 3-6 37 3-8 3-9 3-10

TypicalProgramFlo~ Chart..

IEEE-488 Connector .. ................ .......

IEEE-488Connections~. IEEE-488 Connector Location ...

Contact Assignments

~Generd Data Format

SRQMask and Serial Poll Byte Fo~at.........................................~.....-...-..-

UO Machine Status Word and Default V&es

Ul Error Status Word .... .... ........

Hit Button Command Numbers

...................................

.........................................................................

........................

..............................................................

.._ ........

.................................................

........................

..........................................................

.._..............._ .................

.....................................

~.y.:~I.T ._ ~.~--.~:~.~.~.

....................

~.:.~ ..;

.......................

......................................................

.............................................................................................................

................................

.~.- .. . _~_.~_ _,_

......................................

............................ .

.......

.....

..-

........

..*........~

...... _ .

_,__

........................

.................

.......

...

......

...

.~_.

-.:-~. :;4j

.....

;;.~:3: ...

2-3 2-5

2-10 2-11

2-p $E

2-26 i;g

3-5 3-23 3-24

i;;: 3-32

SECTION 4-PERFORMANCE VERIFICATION

42 43

E 4-6

Conmctions ‘for DC Volts Verification CoMectionsforTRMSACVoltsVeriCication~ Connections for Ohms Verification (300%#$! Range) Connections for Ohms Verification (3OOkn--3OOMQ Ranges) Connections for DC Current Verification Connections for TRMS AC Cur&t Verification ._.

..........................................................

........................................................ 45

SECTION &PRINCIPLES OF OPERATION

5-l 5-2 5-3

S-4 5-5 5-6

Overall Block Diagram. Input Configuration During 2 and 4Terminal Resistance Measurement. Resistance Measurement Simplified Circi&y

JFET Multiplexer

Multiplexer Phases A/D Converter Simplified Schematic

.......................................................................

.........................................................................................................

...........................................................

......

.....

....................................................

...................................................

_:.

.........

...............

......................................

..!.

.......

.........................

........................... 5-3

...............................................

...................

42 43 44 44

4-5

5-2 5-4

5-8

Vii

SECTION 6-MAINTENANCE

DC Volts Calibration Confii&on (300mV ani ,y @nges)

DC Volts Calibration Confi~atio~ (3OV-300V Ranges) ...........................................

Four-Wire Resistance Calibration Configuration (3000-3OkQ Ranges) Two-Wire Resistance Calibration Configuration (300kO3OOMQ Ranges). Flowchart of AC Volts Calibration Procedure TRMS AC Volts Calibration Configuration :.I

TRMS~ AC Volts Calibration Adjustments .......................................................

DC Current Calibration Configuration., .......................................................

ACCurrent CalibrationConfiguration

Analog Board Conne~ors~. ..........

Model196ExplodedViav

....................................................................

SECTION 7-REPLACEABLE PARTS

7-1 7-2 7-3

z 7-6

Display Board, Comporient Location Drawing, Dwg. No. 196-110. Display Board, Schematic Diagram, Dwg. No. 196.XL6 Digital Board, Component Location Drawing, Dwg. No. 196-100 Digital Board, Schematic Diagram, Dwg. No. 196-106. Analog Board, Component Location Drawing, Dwg. No. 196.120

Analog Board, Schematic Diagram, Dwg. No. 196-126

APPENDIX D

D-l D-2 D-3

tEEEBusCon@ration

IEEE Handshake Sequence .......

CommandCodes

............................................................................

......................................................................

......................................

....................................................

.. ;

..................................................

.........................................................

.........................................

..............................................

...............................

...........................................

;Y;~;

..............................................

...............................

............................

.~.-i..

..............

..................................

.................... ;. .. ; . ~; ;

‘.‘~.

.........

..................................

.;.

.............

6-5 6-5 6-6

6-7

6-8

1. ... 6-8

6-9

6-10 6-U.

6-12~

6-l3

~7-4

7-5

....... ; . 7-12

7-13

7-24 7-25

D-l

D-3

D-6

viii

SECTION 1

GENERAL INFORMATION

1.1 INTRODU~ION

The Keithley Model 196 System DMM is a five function autoranging~ digital multimeter. At 6% digit resolution, the LED display can display ~*3,@0,1lOO coo@s. The ran@ of this analog-to-digital (A/D) converter is greater t+q the nor: mal *l,999,999&tit~AAID converter used in many 6% &St DMMs. The built-in IEEE-488~ interface makes the instrument fully programmable over the IEEE-488 bus. The Model 196 can make the following basic measurements:

1. DC voltage measurements from lOOnV to 3OOV.

2. Resistance measurements from lOOpI tb’3OOM62.

3. TRMS AC voltage measurements from 1pV to 300V.

4. DC current me&urements from lnA to 3A.

5. TRMS AC current measurements from lnA to 3A.

In addition to the above~ mentioned measurement capabilities, the Model 196 can make:AC dB voltage and current measurements.

1.2 FEATURES

1.3 WARRANTY INFORMATION

Warranty information may be found on the inside front cover of this manual. Should it become necessary to exq c@e the warranty, contact your Keithley represent&e or the ~factory to determine the proper course of action. Keithley Instruments maintains service facilities in the United States, United Kingdom and throughout Europe. Information concerning the application, operation or service of your instrument may be directed to the applications engineer at any of these locations. Check the inside front cover for addresses.

1.4 MANUAL ADDENDA

Information concerning improvements or changes to the instrument which occur after the printing of this manual will be found on an addendum sheet included with the manual. Be sure to review these changes before attempting to operate or service the instrument.

1.5 SAFETY SYMBOLS AND TERMS

Some important Model 196 features include:

l 10 Character Alphanumeric Display-Easy to read 14seg-

ment LEDs used for readings and front panel messages.

*High Speed Measurement Rate-l000 readings per

second.

l Zero-Used to cancel offsets or establish baselines. A zero

value can be programmed from the front panel or over

the IEEE-488 bus.

l Filter-The weighted average digital filter can be set from

the front panel or over the bus.

l Data Store-Can stoti tip to 500 readings and is accessl%le

only over the bus.

l Digital Calibration-The instrument may be digitally

calibrated from either the front panel or over the bus.

l User Programmable Default Condition&&y inshument

measurement configuration can be established as the power-up default conditions.

l Translator Softwze-User defined words (stored in non-

volatile memory) can be used to replace standard command strings over the IEEE-488 bus.

l Offset Compensated Ohms-Used to correct for small er-

ror voltages in the measurement circuit.

The following safety symbols and terms are used in this manual or found on the Model 196.

The A

symbol on the instrument denotes that the user

should refer tom the -operating instruction iq this manual. The I/y on the instrument denotes that a potential of

300V or more may be present on the terminal(s). Standard safety practices should be observed when such dangerous levels are encomitered.

The WARNING used in this manual explains dangers that could result in personal injury or death.

The CAUTION used in this manual explains hazards that could damage the instrument:

1.6 SPECIFICATIONS

Detailed Model 196 specifications may be found preceding the 7hble of Contents oft &is manual. ~. ~~~~

l-l

1.7 INSPECTION

1.9 GETTING STARTED

The Model 196 System DMM was carefully inspected, both electrically and mechanically before shipment. After unpacking all items from the shipping carton, check for any obvious signs of physical damage that may have occurred during transit. Report any damage to the shipping~agent. Retain and use the original packing materials in case reshipment is necessary. The following items are shipped with every Model 196 order:

Model 196 System DMM Model 196 Instruction Manual

Safety Test Leads (Model 3751) Additional accessories as ordered.

Jf an additional instruction manual is required, order the manual package (Keithley Part Number 196-901-00). The manual package includes an instruction manual and any applicable addenda.

1.8 USING THE MODEL 196 MANUAL

This manual contains information necessrny for operating and servicing the Model 196 System DMM. The information is divided into the following sections:

l Section 1 contains general information about the Model

396 includiig that necessary to inspect the instrument and get it operating as quickly as possl%le.

l Section 2 contains detailed operating information on

using the front panel controls and programs, making connections and basic measuring techniques for each of the available measuring functions.

l Section 3 contains the information necessary to connect

the Model 196 to the IEEE488 bus and program operating modes and functions from a controller.

l Se&on 4 contains performance verification procedures

for the instrument. This information will be helpful if you wish to verify that the instrument is operating in compliance with its stated specifications.

l Section 5 contains a description of operating theory.

Analog, digital, power supply, and IEEE-488 interface operation is included.

0 Section 6 contains information for servicing the instru-

ment. This section includes information on fuse replacement, line voltage selection, calibration and troubleshooting.

l Section 7 contains replaceable parts information.

The Model 196 System DMM is a highly sophisticated instrument with many capabilities. To get the instrument up &id running quickly use the following procedure. For complete information on operating the Model 196 consult the appropriate section of this manual.

Power up

1. Plug the line cord intom~the rear anel power jack and plug the other end of the cordpinto an appropriate,

grounded power source. See paragraph 2.2.1 for more complete information.

2. Press in the POWER switch to apply power to the in-

shument. The instrument will power up in the 3CW DC

*ange.

Making Measurements ‘L Connect safety~shrouded testy leads to the front panel

VOLTS H.I and LO input terminals. Make sore the INPUT switch on the rear panel is in the in (FRONT)

position.

2. To make a voltage measurement, simply connect the in-

put leads to a DC voltage source (up to 3OOV) and take the reading from the display.

3. To change to a different measuring function, simply press the desired function button. For -pie, to measure resistance, press the OHMS button.

Using Front P.&e1 Programs Program selection is accomplished by pressing the PRGM

button followed by the button(s) eat corresponds to the program number or name. For example, to select Program 31 (IEEE), press the PRGM button and then the 3 and 1 buttons. ‘Ihble 2-7 lists and briefly describes the available front panel programs. Once a program is selected the following general rules will apply:

1. A displayed program condition can be entered by pressi”p the ENTER button.

2. Program conditions that prompt the user with a flashing

digit can be modified using the data buttons (0 through 9 and i).

3. Programs that contain alternate conditions can be

displayed by pressing one ofthe range buttons. Each press of one of these buttons toggles the display between the two available conditions.

1-2

GENERAL INFORMATION

4. A program will be executed when the ENTER button is pressed.

5. A program can be exited at any time and thus not eyecuted, by pressing the PRGM button.

Paragraph 2.7 provides the detailed information for using the front panel programs.

1.10 ACCESSORIES

The following accessories are available to enhance the Model l96s, capabilities.

Models lOl9A and 1019s Rack Mounting Kits-The Model

~1019A is a stationary rack mounting kit with two front

panels provided to enable either single or dual side-by-side mounting of the Model 196 or other similar Wthley instruments. The Model 10195 is a similar rack mounting kit with a sliding mount configuration.

Model X301 Temperature Probe-The Model 1301 is a rUgged low cost temperature probe designed to allow temperature measurements from -55 to I5O’C.

Model 16008 High Voltage Probe-The Model 16008 extends

DMM measurements to 40kV. Model 165150Ampere Current Shunt-The Model 1651 is

an external 0.00161 +J% 4terminal shunt, which permits current measurements from 0 to 50A AC or DC.

Model l&31 Clip-On Test Lead Set-The Model l68l’con tains two leads, 1.2m (4 ft.) long terminated with banana plugs and spring action clip probes.

Model 1754 Universal Test Lead Kit--The Model 1754 is a

12 piece test lead kit, with interchangeable plug-in accessories. Included in the kit is one set of test leads (l-red, l-black), two spade lugs, two standard b-a plugs, two phone tips (0.06 DIA.), two hooks and miniature alligator clips (with boots).

Model 5804 Test Lead Set-The Model 5804, used for 4terminal measurements, includes: two test probes with spring-loaded plunger clip adapters to fit test probes, two spring-loaded plunger test clips with in-line banana jacks, and four solid copper alligator clips with insulator boots.

Model 5805 Kelvin Probes-The Model 5805 includes two spring-loaded Kelvin test probes (one red, one black), with 48-inch banana plug cable assemblies. A set of eight replacement contacts for the Model 5805 Kelvin test probes is also available (Keithley PIN CS-551).

Model 5806 Kelvin Clip Lead Set-The Model 5806 includes

~two I+in clip test lead assemblies with banana plug ter-

mination (one red, one black). A set of eight replacement rubber bands for the lviode1~5806 is also available (Keithkey PIN GA-22).

Model 7087 IEEE-&3 Shielded Cables-The Model 7007 connects the Model 196 to the IEEE-488 bus using shielded cables to reduce electromagnetic interference (EMI). The Model 7Ow-1 is one meter in length and has a EMI shielded IEEE-488 connector at: each end. The Model 7007-2 is identical to the Model 7007-1, but is two meters in length.

Model 7088 IEEE488 Cables-The Model 7008~connects the Model 196 to the IEEE-488 bus. The Model 7008-3 is D.9m

(3 ft.) in length and has a~standard IEEE488 connector at each end. The Model 7008-6 cable is identical to the Model 7008-3, but~is 1.8m (6 ft.) in length.

Model 1682A RF Probe-The Model 1682A permits voltage measurements from lOOkHa to 25OMHz. AC to DC transfer accuracy is *ldB from lOOkFIr to 25OhJH.z at IV, peak responding, calibrated in RMS of a sine wave.

Model 1685 Clamp-On AC Probe-The Model 1685 measures AC current by clamping on to a single conductor. Interruption of the circuit is unnecessary. The Model

1685 detects currents by sensing the chsnglng magnetic field

produced by the current~flow.

Model I751 Safety Test Leads-Finger gu$.s and shrouded banana plugs help minimize the chance of making contact

with live circuitry.

Model 8573A IEEE488 Interface--The Model 8573A is an IEEE1188 standard interface designed to interface the IBM PC or XT computers to Keithley instrumentation over the

~IEEE-488 bus. The interface system contains two distinc-

tive parts an interface board containing logic~ to perform

the necessary hardware functions and the handler software (supplied on disk) to perform the required control func-

tions. These two important facets of the Model 857ZA join together to give the IBM advanced capabilities over lXE-488 interfaceable instrumentation.

l-311-4

SECTION 2

BASIC DMM OPERATION

2.1 INTRODUCTION

Operation of the Model 196 can be divided into two general

categories: front panel operation and IEEE-488 bus~operation. This section contains information necesssay to use the instrument from the front panel. Theses functions can also be programmed over the lEFE-488 bus, as described in Section 3.

2.2 POWER UP PROCEDURE

2.2.1 Line Power

Use the following procedure to connect the Model 196 to line power and power up the instrument.

1. Check that the instrument is set to correspond to the available line power. When the instrument leaves the factov, the internally selected line voltage is marked on the rear panel. Ranges are 105W25V or 2kW!5OV 5016OHz AC. If the line voltage setting of the instrument needs to be changed, refer to Section 6, paragraph 6.2 for the procedure. If the line frequency setting of the instrument needs to be checked and/or changed, utilize front panel Program 32 (see paragraph 2.7.8) after the instrument completes the power up sequence.

2. Connect the female end of the power cord to the AC receptacle on the rear panel of the instrument.~ Connect the other end of the cord to a grounded AC outlet.

WARNING The Model 196 is equipped with a 3-wire power cord that contains a separate ground wire and

is designed to be used with grounded outlets,

When proper connections are made, instrument chassis is connected to power line ground.

Failure to use a gmunded outlet may result in personal injury or death because of electric shock.

CAUTION

Be sure that the power line voltage agrees with the indicated range on the rear panel of the instrument. Failure to obsenre this precaution may result in instrument damage.

2.2.2 Power Up Sequence

The instrument can be turned on by pressing in the front panel POWER switch. The switch will be at the inner most position when the instrument is turned on. Upon ower up, the instrument will do a number of tests on itse 9 Tests are performed on memory (ROM, RAM and ETROM). If RAM or ROM fails, the instrument will lo& up. If ETROM FAILS, the message ‘TINCAL!’ will be displayed. See paragraph 67.2 for a complete description of the power up self test and recommendations to resolve failures.

2.2.3 Default Conditions

Default conditions can be defined as setup conditions that the instrument will return to when a particular feature or command is asserted. The Model 196 will return to either factory default conditions or user saved default conditions.

Factory Default Conditions Ate the factory, the Model 196 is set up so that the instru-

ment is configured to certain setup conditions on the initial power up. These factory default conditions are listed in Tables 2-l and 37 (located in Section 3). If alternate setup conditions are saved (see User Saved Default Conditions), the instrument can be returned to the factory default con-

ditions by running Program 37 (Reset). To retain the fac-

tory default condihons as power-up default conditions, run Program 30 (Save} immediately after executing kograrn 37 (Reset).

Sending device-dependent comman d I.0 over the IEEE-488 bus is equivalent to running Program 37 (Reset) and then Program 30 (Save).

2-l

Table 2-1. Factory Default Conditions

2.3 FRONT PANEL FAMILIARIZATION

Control/kahw

Zero value (rrogram ZERO)

dB dB Reference Value

(program dB) Filter Filter Value (Program FILTER)

MX+B Status (Program 4)

MX+B Parameters (Program 34) Multi

NOTE: The Model 196 is initially set for an IEEE address of 7. The line frequency is set to 50 nor 6OHz.

User Saved Default Conditions

Each function oft the Model 196 “remembers”~ the last measurement configuration that it was set up for (such as range, zero value, filter value, et+ Switching back and forth between functions will not affect the unique tonfiguratioq of each function. However, the instrument will “forget” the configurations on power-down unless they are saved.

Unique setup conditions can be saved by running front panel Program 30 (Save) or by sending device-dependent command Ll aver the IEBE-488 bus. These~tiser saved default conditions will prevsjl over the factory default conditions on power-up, or when a DCL or SDC is asserted over the bus.

IEEE Address and Lie Frequency Any IEEE address and line frequency setting can be saved

as default conditions by running Program 30 (Save) or by sending Ll over the bus. See paragraph 2.7 for complete information on Programs 31 (IEEE Address) and 32 (Line Frequency).

lexer (Program 6) ‘-’

HI/ LB

/l’ASS~~(l’rogrsm 5)

HI/Lo Limits (Program 35)

Ohms Compensation (Program R

kfault Condition

DCV 3cQV

6% Di ‘ts

Diiabgd

000.0000

Disabled

1.000000

Disabled

M=1.0OWOO~ ;~~

3=000.0000

Enabled

Disabled

+3.030000,

-3.o3clooo

Disabled

The front panel layout of the Model 196 is shown in Fiie Z-l. The following paragraphs describe the various components of the front panel in detail.

2.3.1 Display and Indicators

Display-The 10 character, alphanumeric, LED display is used to display numeric conversion data, range and function mnemonics (i.e. mv) and messages.

Function Indicators-The indicator that is on identifies which of the five operating functions is currently selected.

Rsnge Jndicator-When the instrument is in autorange the AUTO indicator light will be on.

Modifier Indicators-When the zero feature is enabled, the ZERO indicator will torn on. When filter is enabled, the FKTER indicator will turn on.

IEEE Status Indicators-These three indicators apply to instrument operation over the IEEE-488 bus. The RMT indicator shows when the instrument is in the IEEE-488 remote state. The TLK and LSN indicators show when the instrument is in the talk and listen states respectively. See Section 3 for detailed information on oueration over the bus.

2.3.2 Controls

.&lI front panel co&ols, except the POWER and C%L ENABLE switches, are momentary contact switches. Indicaton are located above certain buttons to show that they are enabled. Some buttons have secondary functions that are associated with front panel program operation. See paragraph 2-7 for detailed information on front panel prOg.3lllS.

POWER-The POWER switch controls AC power to the insbxment . Depressing and releasing the switch once tams the power on. Depressing and releasing the switch a second time turns the power off. The correct positions footi\and off are marked on the front panel by the POWER

El FUNCTION GROUP

NOTE

An ‘TJNCAI!’ error will set the IEEE address to 7 and the line frequency to 6OHz.

2-2

DCV-The DCV button places the instrument in the DC volts measurement mode. The secondary function of this

button is to enter the i sign. See paragraph 2.6.4 for DCV

measurements.

BASIC DMM OPERATION

Figure 2-1. Model 196 Front Panel

ACV-The ACV button places the instrument in the AC volts measurement mode. The secondary function of this button is to enter the number 0. See paragraph 26.7 for ACV measurements.

&The fl button places the instrument in the ohms measurement mode. The secondary function of this button is to enter the number 1. See paragraph 2.6.6~for resistance measurements.

DCA-The DCA button places the instrument in the DC amps measurement mode. The secondary function of this button is to enter the number 2. See paragraph 26.8 for DC4 measurements.

ACA-The ACA button places the instrument in the AC

amps measurement mode. The secondary function of this

button is to enter the number 3. See paragraph 2.6.8 for ACA measurements.

RANGE GROUP

!zl

Manual-Each time the A button is pressed, the instrument will move up one range, while the V button will move

the instrument down one range each time its is pressed. Pressing either of these buttons will cancel autorange, if it was previous selected. The secondary functions of these buttons are tom enter the number 4 (V) and number 5 (A).

AUTO-The AUTO button places the instrument in the autorange mode. While in this mode, the instrument will go to the best range to measure the applied signal. Autoranging is available for all functions and ranges. Autoranging may be cancelled by pressing the AUTO button or one of the manual range buttons. The secondary function of this button is to enter the number 6.

ZERO-The ZERO button turns on the ZERO indicator and causes the displayed reading to be subtracted from subsequent readings. This feature allows for zero correction or storage of baseline values. The secondary function of this

button is to select the ZERO program and enter the number

Z Refer to paragraph 2.62 for detailed information on the

zero feature.

2-3

SAS\C DMM OPERATION

FIUER-The FIWER button turns on the FIUEl7 indicator and causes the instrument to start weighted averaging (1 to l/99) fhe readings. The factory default weighted average is l/10, but may be changed using the PIITER program (see paragraph 2.7.16). See paragraph 2.6.3 for filter operation. Selectin the PILTEK rogiam is one of the secondary functionsof&isbutton.&eothersecondaryfunctionisto~nter the number 8.

dB-The dB button places the inshument~~in the dB measurement mode and may be used with the ACV and ACA functions. Under factory default conditions, measure-

ments are referenced to 1V or lmA. However, the dB program may be used to change the referqce @ell. ‘JTh$ seconY day function of this button is to select the dB program and enter the number 9. See paragriph 2.6.9 for dB measurements.

CONTROL GROUP

PRGM-This button is used tom enter the fronts panel pro-

gram mode.

ENTER-This button is used to enter program parameters. This button will also trigger a reading when the instruments

is in a one-shot trigger mode.

the LOCAL button will be inoperative. See Section 3 for informa$on on operating the instnunent-over the IEEE488

bus.

2.3.3 Input Terminals q

The ~input terminals are intended to be used with safety shrouded test leads to help minimize the possibility of contact with live cikuits. Note that the terminals sre duplicated sideways on the rear panel and that the INPUT switch (also located on the rear panel) determines which set of termin& is Bctive.

VOLTS 0HMS~i-J.I akd LQ-l’he VOLTS OHMS Hl atid LO terminals are used for making DC volts, AC volts and two-

wire resistance measurements. AMPS and LO-The AMPS and LO terminals are used for

making DC current and AC cUrrent measurem&s. OHMS SENSE HI and LO--The OHMS SENSE HI and LO

terminals are used with the VOJXS OHMS HI and LO terminals to make four-wire resistance measurements.

El LQCA&When the instrument is in the IEEE-488 remote state (RM’I indicator on), the LOCAL button will return the instrument to front panel operation. However, if local lockout (LLO) was asserted over the IEEE-488 bus,

2.3.4 Calibration Enable Switch q

Calibration of the Model 196 can only be done if the CAL ENABLE switch is in the enable position. See paragraph

6.4 for details.

2-4

BASIC DMM OPERATION

2.4 REAR PANEL FAMILIARIZATION

The reax panel of the Model 196 is shown in Figure 2-2.

2.4.1 Controls

ra T TkTc TIC%TTA,-C -t-L:- a.r.2~L -A,-~ the hment

Iable lme voltage. see paragrapn 6.2 for the proset this switch.

INPUT-The INPUT switch connects the instrument to either the front panel input terminals or the rear panel input terminals. This switch operates in same manner as the power switch. The front panel input terminals are selected when the switch is in the “in’ position and the rear panel input terminals are selected when the switch is in the “0uV position.

2.4.2 Connectors and Terminals

~~~ pJ

AC Receptacle-Power is applied through the supplied power cord to the 3-terminal AC receptacle. Note that the selected supply voltage is marked on the rear panel near the line voltage switch.

El Input Terminals-The rear panel input terminals per-

form the same functions as the front panel input terminals. Paragraph 2.3.3 contains the description of the input terminals.

mu IEEE-488 Car

nect the ins,e functions ym -rl-l

used to apply pulses to trigger the Model 196 to take one or more readings, depending on the selected trigger mode.

x5 14,&ed below the connector.

EXTERNAL TRIGGER Input-This BNC~connector is

mector-This connector is used to connt to the IEEE-483 bus. IEEE interface

Figure 2-2. Model 196 Rear Panel

2-5

BASIC DMf.4 OPERATION

VOITMFXER COMPLETE Output-T% BNC output connector provides a TTLcompatible negative-going pulse when the Model 196 has completed a reading. It is useful for triggering other inshumentation.

2.4.3. Fuses

LINE FUSE-The line fuse provides protection for the AC power line input. Refer to paragraph 6.3.1 for the line fuse replacement procedure.

CURRENT FUSkhe 3A current fuse provides protection for the current measurement circoits of the instrument. Refer to paragraph 63.2 for the cwr$nt fuse replacement procedure.

To optimize safety when measuring voltage in high energy distribution circuits, read and use the directions in the following warning.

WARNING Dangerous arcs of an explosive nature in a high energy circuit can cause severe personal injury or death. If the meter is connected to a high energy circuit when set to a current range, low resistance range or any other low impedance range, the circuit is virtually shorted. Dangerous arcing can also result when the meter is set to a voltage range if the minimum voltage spacing is reduced.

2.5 ERROR DISPLAY MESSAGES

Table 2-2 lists and explains the various display messages assodated with incorrect front panel operation of the Model

196.

Table 2-2. Error Messages

Message

UNCAL

NO PROGRAM

O.VERFLO KQ

TRIG-ERROR

AC ONLY

NO RANGE

CONFLICI

Explanation

EIPROM failure on power up. See paragraph 6.7.2. Invalid entry while trying to select program. Overrange-Decimal point position and mnemonics define function and range (3kfl range shown).~ Th: number of characters in the “OVERFLO” message defines the display resolution (6Yzd resolution

shown). Trigger received while still processing reading from last trigger.

Selecting dB with in&ument fitit in ACV or ACA. Pressing a range button while in ACV dB or ACA dB. 196 in invalid state (i.e. dB function), when entering calibratioti p*ogram.

2.6 BASIC MEASUREMENTS

When making measurements in high energy circuits use test leads that meet the follcwing requirements:

l Test leads should be folly insulated. l Only use test leads that can be connected to the circuit

(e.~,jz~~~~.clips, spade lugs, etc.) for hands-off

l Do not use test leads that decrease voltage spacing. This

diminishes arc protection and creates a hazardous condition.

Use the following sequence when testing power circuits:

1. De-energize the circuit using the regular installed connect-disconnect device such as the circuit breaker, main switch, etc.

2. Attach the test leads to the circuit under test. Use appropriate safety rated lead~s for this application.

3. Set the DMM to the proper function and range.

4. Energize the circuit using the installed connectdisconnect device and make measurenwnts without disconnecting the DMM.

5. De-energize the circuit using the installed connectdisconnect device.

6. Disconnect the test~leads from the circuit under test.

WARNING The maximum common-mode input voltage (the voltage between inout LO and chassis around) is 506J peak. Exceeding this value may create s shock hazard.

The following paragraphs describe the basic pwxdures for making voltage, resJs@~ce, current, and~dB measurements.

2-6

BASIC DMM OPERATION

2.6.1 Warm Up Period

The Model 196 is usable immediately when it is first turned on. However, the instrument must be allowed to warm up for at least~ two hours to achieve rated accuracy.

2.6.2 Zero

The zero feature serves as a means of baseline suppression by aIlowing a stored offset value to be subtracted from

subsequent readings. When the ZERO button is pressed, the instrument takes the currently displayed reading as a baseline value. All subsequent readings represent~the difference between the applied signal level and the ~stored baseline.

A baseline level can be established for any or all measure-

ment functions and is remembered by each function. For

example, a 1OV baseline can be established on DCV, a 5V

baseline can be established on ACV and a 1Okll baseline

can be established on OHMS. Theses levels will snot be

cancelled by switching back and forth between functioti.

Once a baseline is established for a measurement function,

that stored level will be the same regardless of what range

the Model 196 is on. For example, if 1V is established

as the baseline on the 3V range, then the baseline will also

be 1V on the 30V through 30lV ranges. A aem baseline level

canbeaslaigeasfullrange. ~~

NOTE

The followirg discussion on dynamic range is

based on a display resolution of 6% digits. At 5’/zd resolution, the number of counts would be reduced by a factor of 10. At 4Yzd resolution, counts would be reduced by a factor of 100 and 3%d resolution would reduce counts by a factor of 1000.

Example l-The instrument is set to the 3V DC range and a maximum -3.03OOOOV is established as the zero value.

When -3.03OOOOV is connected to the input of the Model 196, the display will read O.OMlOOClV. When +3.03OCEOV is co.nnected to the input, the display will read +60600ooV. Thus, the dynamic measurement range of the Model 196 is OV to 6.06V, which is 6060000 counts.

Example 2-Ihe instrument is still set to the 3V DC range, but a maximum +3.03oOOOV ia the zero level. When

+3.03oO~CGV is connected to the input of the Model 196, the display will read O.O@XtOOV When Y3.0~ is connected to the input, the display will read -6.06OOOCV. Thus the dynamic measurements range of the instrument is -6.06V to OV, which is still 6060000 counts.

Zero Correction-The Model 196 must be properly zeroed when using the 3OOmV DC or the 3OOB range in order to

achieve rated accuracy specifications. To use ZERO for zero

correction, perform the following steps:

Disable zero, if presently enabled, by pressing the

ZERO button. The ZERO indicator will turn off. Select the 3oOmV DC or the 30022 range.

2. Connect the test leads to the input of the Model 196 and

3. short them together. If four-wire resistance measurements are to be made, connect and short all four leads together. Allow any thermals to stabilize.

Note: At5% and 6%~digit resolution, low level measurement techniques need to be employed. Use Kelvin test leads or shielded test leads. See paragraph 2.6.5 for low level measurement considerations.

Press the ZERO button. The display will read zero.

4. Remove the short and connect thetest leads to the signal

5. or resistance to be measured.

Note: Test lead, resistance is also~ compensated for when zeroing the 3OO’J range with the above procedure.

By design, the dynamic measurement range of the Model

196, at 6%-d@ resolution, is M)60000 counts.1 With zero disabled, the displayed reading range of the instrument is

*303ooOO counts. With zero enabled, the Model 196 has

the capability to-display ~606OCOO counts. This increased

display range ensures that the dynamic measurement range of the instrument is not reduced when using a zero baseline

value. The following two examples will use the maximum

allowable zero values (3030000 counts and -3030008 counts) to show that dynamic measurement range wilI not

be reduced. It is important to note that the increased display

range does not increase the to the instrument. For example, on the 3V range, the Model 196 will always overrange when more than k3.03V is connected to the input.

maximum allowable input level

Baseline Levels-Baseline values can be established by either applying baseline levels to the instrument or by setting baseline values with the front panel ZERO program. paragraph 27’15 contains the complete procedure for using the ZERO program. To establish a baseline level by applying a level to the Model 196, perform the following steps:

1. Disable zero, if presently enabled, by pressing the ZERO button. The ZERO indicator will turn off.

2. Sele&a function and range that is appropriate for the

anticipated measurement.

3. Chnect the desired baseline level to the input -of the

Model 196 and note that level on the display

2.7

BASIC DMM OPERATION

4. Press the ZERO button. The display will zero and the ZERO indicator will be enabled. The previously

displayed reading will be the stored baseline. The rero baseline value will also be stored in Program ZERO, replacing the previous zero value.

WARNING

With ZERO enabled, a hazardous voltage

baseline level (rt4OV or more), not displayed, may be present on the input terminals. If not sure what is applied to the input, assume that a hazardous voltage is present.

5. Disconnect the stored signal from the input and connect the signal to be measured in its place. Subsequent~

readings will be the difference between the stored value and the applied ‘signal.

Notes:

1. Disablmg zero cancels the zero baseline value on that

selected function. However, since the zero value is automatically stored in Program ZERO, the zero baseline value can be retrieved by using the program as long as

the ZERO button is not ~again pressed (see paragraph

2.Xi5 for details). Pressing the ZERO button, thus enabling zero, will wipe out the previous baseline value in Pro-

gram ZERO. Baselines established on other functions are not affected.

2. To store a new baseline on a selected function, zero must first be disabled and then enabled again. The new value will be stored with the first triggered conversion. The baseline value wi.lI also be stored as~the zero value in Program ZERO, cancelling the previously stored value.

3. Setting the range lower than the suppressed value wi.lI overrange the display; the instrument will display the

overrange message under theses conditions.

4. When the ZERO button is pressed to enable zero, the ZERO indicator light will blink until an on scale reading is available to use as a zero level.

2.6.3 Filter

The Model 196 incorporates two filters; a digital filter controlled from either the front panel or over the IEEE-438 bus,

and an internal filter controlled exclusively from over the

bus.

The factory default filter weighting is l/l@ but can be changed to a weighting from 1 (l/l) to-1199 with the use of the FILTER program. While in the program, the Model 196 will only display the denominator of the filter Weighting. For example, if the current filter weighting is l/lo, the FILTER program will display it as the value l0. Thus, filter value as usecl in this discussion refers to the values displayed by the Model 196 when in the FILTER program.

A falter value can be set for any or all measurement functions and is remembered by each function. For example, a filter value of 20 can be set for DCV and a filter value of 53 can be set~for ACV These filter values will not be cancelled by switching back and forth between functions.

An advantage of using the filter is to stabilize the reading

-of a noisy input level. A consideration of filter usage is that the larger the weighting, the longer the response time of the display. Perform the following procedure to use the filter:

1. If it is desired to cb.eck and/or change the filter value, utilize Program FIITER as explained in paragraph 27.16.

2. Press the FILTER button. The FILm indicator will turn on.

Notes:

1. When the filter is enabled, readings will be filtered before being displayed. See Digital Filter Theory.

2. Pressing the FILIER button a second time will disable the filter.

3. After a reading is triggered (continuous or one-shot), the FIITER indicator light will blink for three time constants. A time constant is measured in readings. The number of readings in one time constant is equal to the filter value. For example, for a filter value of IO, one time constant~ is equal to 10 readings and three time constants would be equal to 30 readings. The blinking duration will be shorter in the 3%d mode since that has the fastest reading rate.

4. In a continuous trigger mode, a reading that is outside the filter window wiIl cause the FILTER indicator to blink for one time constant.

Digital Filter Theory-The mathematical representation of the weighted average digital Elter is as follows:

Digital Filter-The Model 196 utilizes a digital filter to attenuate excess noise present on input signals. This filter is a weighted average type.

2-6

(new reading -AVG(t-I))

AVG(t) = AVG(t-1) +

BASIC DMM OPERATION

where,

AVG(t) = displayed average AVG(t-1) = old displayed average

F = weighting factor (filter value)

As with any filter, the Model 196 digital filter will affect reading response time. The step response for this fiker~is of the form:

step response = l-K’“+”

Where,

“K” is a constant based on the filter weighting~ factor

The step occurs when n=O. n=l is the first ream after

the step, n=2 is the second reading, etc. Therefore:

a+1

step response = l-

Example: F=10

n=5

l- Y-

( )

displayed value will be the new reading, and weighted averaging WilI start from this point. The step response was one reding to tbis change. The window in the Model 196 filter is lO,OoO counts for 6Yzd resolution, 1000 counts for 5Yzd, 7.00~ counts for 4Yzd and 10 counts for 31/2d.

Internal Filter-In addition to the front panel digital filter, an inter& running avenge digita~fiher & -cd when msking high ~oh$ion and high sensitivity rriek+reme$k qe enable&able status of the filter is controlled over the IEEE bus. However, under factory default conditions, the in&~ment powers up with the filter enabled. When enabled, this filtering only occurs when the instniment is in the 5Yz OI blh-digit resolution niode.

Notes:

1. The front panel FILTER indicator light does not turn on when the internal filter is activated. The indicator is only used with the front~panel digital filter.

2. Contding the internal filter (on/off) over the IEEE bus

is explained in paragraph 3.9.22.

3. In a one-shot trigger mode, the Model 196 will not output a reading until both filters have settled. Three time

constants are used to allow the filters to settle. A time constant is measured in readings. The number of readings in one time constant is equal to the filter value. For example, for a filter value of lo,, three time constants would be equal to 30 readings. If both the internal filter and the front panel filter are in use, the time constant is the sum of both filter values.

4. Filter windows for the internal filter function in the same

manner as the windows for the front panel filter. However, the window sizes of the internal filter are much bnaller than the front panel filter window sizes.

Five readings sfter the step occurs, the display will be at

47% of the step change. After 10 readings (n=lO), the display will be at 168% and after 20 readings, the display wiU be at ~88%. The more the readings, the closer the display will be to the step change.

To speed the response to large step changes, the Model 196

digital filter employs a “windo+ around the displayed average. As long as new readings are within this window,

the displayed value is based on the weighted avemge equa-

tion. If a new reading is outside of this window, the

2.6.4 DC Voltage Measurements

The Model 196 can be.~ used tom make DC voltage measurements in the range oft-*XlOnV to k3OOV. Use the following procedure to make DC voltage measurements.

1. Select the DC volts fundion by pressing the DCV button.

2. Select a range consistent with the expected voltage or use autorange.

3. Select the front or rear panel input terminals with the INPUT switch.

NOTE

The 3oOmV DC range requires zero to be set in

order to achieve rated accuracy. The zero correction procedure can be found in paragraph 2.6.2.

2-9

BASIC DMM OPERATION

4. Connect the signal to be measured to the selected input terminals as shown in Figure 2-3.

5. T&e the reading from the display

CAUTION:

MAXIFIUM INPUT

INPUT RESISTANCE

= 300V RtlS. 425V PEAK = WJdiM:;Vs > IGIl

300G: 10.llln

Figure 2-3. DC Voltage Measurements

2.6.6 Low-Level Measurement Considerations

Accuracy Considerations-For sensitive measurements,

other external considerations besides the Model I.96 will affect the accumcy. Effects not noticeable wheti working

with higher voltages sre significant in nanovolt and

microvolt signals. The Model 196 reads only the signal received at its input; therefore, it is important that tb.is signal be properly bansmitted from the source. The following paragraphs indicate factors which affect accuracy noise, source resistance, thermal emfs and stray pick-up.

Noise and Source Resistance-The limit of sensitivity in

measuring voltages with the Model 196 is determined by

the noise present. The noise voltage at the Model 1% input increases with sauce resistance.

For high impedance sources, the generated ~noise can become significant when using the most sensitive mnge

(3COmV, 6Yzd) of the Model 196. As an -pie of determining e, (noise voltage generation due to Johnson noise of the somce resistance), assume that the Model 196 is con-

nected to a voltage source with an internal resistance of

lM0. At a mom temperature of 20°C, the p-p noise Voltage

generated over a bandwidth of lHz will be:

635xXP’~Rxf

e, = e, = 6.35 x lP d/(1 x W) (1)

Thus, an e, of 0.635pV would be displayed at 6Yzd resolulion as an additional six diaits of noise on the Model 196. To compensate for the dispgyed noise, use digital filtering and then zero out the settled offset.

..~

Shielding-AC voltages ‘Which &e extremely k&i cornpared with the DC signal may erroneously produce a DC output. Therefore, if there is AC interference, the~~circuit

should be shielded with the shield connected to the Model

196 input Lo (particularly for low-level sources). Impropw shielding can cause the Model 1% to behave in one or more of the following ways:

1. Unexpected offset voltages.

2. Inconsistent readings between ranges.

3. Sudden shifts in reading.

To minimjze pick-up, keep-the voltage source and the Model 196 away from strong AC magnetic sources. The voltage induced due to magnetic flux is proportional to the area of the loop formed by the input leads. Therefore, minimize the loop area of the input leads and connect each

signd at ody one point.

T&rmal EMFs-Thermal emfs (thermoelectric potentials) are generated by thermal differences between the junction of dissimilar metals. These can be large compared to the

signal which the Model 196 can measure. Thermal emfs can cause the following problems:

-1. Instability or zero offset is much higher than expected.

2. The reading is sensitive to (and responds to) temperature changes. This can be demonstrated by touching the circuit, by placing a heat source near the circuit or by a

regular pattern of instability (corresponding to heating and air-conditioning systems or changes in sunlight).

3. To minim&e the drift caused by thermal emfs, use copper leads to connect the circuit to the Model 196. A banana plug is generally suitable and generates just a few microvolts. A clean copper conductor such ss #lO bus wire is about the best for this application. The leads

to the input may be shielded or unshielded, as necessary.

Refer to Shielding.

Widely varying temperatwes within the circuit can also create thermal ends. Therefor& maintain Constant temperatures to

minimize these thermal ends. A card-

board box around the circuit under test also helps by

minimking air currents.

5. The ZERO cOntro1 can be used to null out constant off-

set voltages.

2-10

e, = 0.635fiV

BASIC DMM OPERATION

2.6.6 Resistance Measurements

The Model 196 can make resistance measurements from

lOO#-l to 3CGMtI. The Model 196 provides automatic selection of 2-terminal or 4terminal resistance measurements. This means that if the ohms sense leads are not connected, the measurement is done Zterminal. If the sense leads are connected, the measurement is done 4terininaI. For 4terminal measurements, rated accuracy can be obtained

as long as the msximum lead resistance does not exceed the values listed in Table 2-3. For best results on the 3008

3kQ and 3OkQ ranges, it is recommended that 4terminal

measurements be made to eliminate errors caused by the

voltage drop across the test leads which will occur when

2-terminal measurements are made. The Model 5806 Kelvin

Test Lead Set is ideal for low resistance 4terminal

Offset-Compensated Ohms-Offs&-compensated ohms is used to compensate for voltage potentials (such as thermal EMFs) across the device under test. This feature eliminates errors due to a low level external voltage source configured in series with the unknown resistor. Offsets up to KhnV on the 3OOn range and up to BlOmV on the other ranges

can be corrected with offset-compensation. This feature can be used for both 2-terminal and 4terminal resistance measurements up to 30k61. Offset-compensation is selected through front panel Program !I (see paragraph 27.14).

especially the 3000 range. After offset-compep.sation is enabled, the Model 1% should be properly zeroed.

To make resistance measurements, proceed as follows:

L Select the ohms function by pressing the Q button.

2. Select a range consistent with the expected resistance or

use autorange.

3. Select the f&t or rear panei input terminals using the INPUT switch.

4. Turn offset-compensation on or off as needed, using Pm-

gram 0.

NOTE

If offset-compensatio~n is being used, the 3ooI1,

3ka and 3OkQ ranges require zero to be set in

order to achieve the best accuracy. The zero car-

rection procedure is located in paragraph 2.6.2.

5. For 2-terminal measurements connect the resistance to the instnunent as shown in Figs 2-4. For 4terminal measurements connect the resistance to the instrument as shown in F&ire 2-5.

CAUTlON

During ohms offset compensated resistance measurements, the Model 196 performs the following steps for each conversion:

1. Makes a normal resistance meaS,mment of the device. In general, this consists of sourcing a current thmu the device, and measuring the voltage dmp acro~ device.

2. Turns off the internal -nt source and again measures

the voltage drop across the device. This is the voltage caused by an external source.

3. Calculates and displays the corrected resistance value.

Offset-Compensated ohms not only cowxts for small error voltages in the measurement circuit, but also compensates for thermal voltages generated withim the Model 196. In normal ohms, these thermal EMF offsets are accounted for during c&ration. Therefore, enabling offset-compensation wilI cause these offsets to appear in the’ readings, Figure 2-4. Two-Terminal Resistance Measurements

tfz

The maximum input voltage between the HI anti LO input terminals is 425V peak or 300V

RMS. Do not exceed these values or instru- ment damage may occur.

6. Take the reading from the’display.

OPTIONAL SHIEY

SHKEf~D

NODEL 196

---

I-

L---~-I

UNDER TEST

2-11

BASIC DMM OPERATION

OPTIONAL SHIELO

-~~- -

B.&rward bias the diode by connecting the red terminal

of the Model 196 to positive side of the diode. A good diode will typically measure between 3OOn to IkQ.

C.Reverse bias the diode by reversing the connections

on the diode. A good diode will overrange the display.

MODEL 196

Figure 2-5. Four-Terminal Resistance Measurements

MODEL 196

CAUTION:

MAX I MUM INPUT = 300V RMS, 425V PEAK. 1O’V.H. INPUT IMPEDANCE = 1Hf-1 SHUNTED BY < 120pF

Figure 2-6. TRMS AC Voltage Measurement

Notes:

1. With ohms compensation active (Progam a), the 61 indicator light will blink when the ohms function is

selected.

2. Table 2-3 shows the current output for each resistance range.

3. It helps to shield resistance greater than IOOkQ to achieve a stable reading. Place the resistance in a shielded enclosure and electrically connect the shield to the LQ input terminal of the instrument.

4. Diode Test-The 3kQ range can be used to test diodes as

MlOWS: A. Select the 3kO range.

Table 2-3. Resistance Ranges

Maximum Test Lead

6%d Nominal Resistance (Q) for

Range 1 Resolutim I-Short 1 -3 Count Error (Wzd)

I I

*5%d resolution only

NOTE: Typical open circuit voltage is 5V.

2.6.7 TRMS AC Voltage Measurements

The instrument can make TRMS AC voltage measurements from l$I to 3OOV. To measwe AC volts, proceed as follows:

1. Select the AC volts function by pressing the ACV button.

2. Select a range con$stent with the expeqed voltage or use autorange.

3. Select the front or rear panel input terminals using the

INPUT switch.

NOTE

There is a small amount of offset (typically 150

counts at 5%d) present when using the ACV function. Do not zero this level o-ut. Paragraph 2.6.10

provides an explanation of AC voltage offset.

2-12

4. Connecbthe signal to be measured to the selected input

terminals as shown in Figure 2-6.

5. Take the reading from the display.

BASIC DMM OPERATION

Clarifications of TRMS ACV Spedfications:

”

Msximum Allowable Input-The following graph summarizes the maximum input based on ~the lWV*Hz

specification.

MAXIIIUH INPUT TRt4S AC VOLTS

FREOUENCY-HZ

2.8.8 Current Measurements (DC or TRMS AC)

The Model 196 can m&e DC or TRW AC current measure:

ments from lnA (at 5Yrd resolution) to 34. Use the following procedure to make current measurements.

1. Select the DC current or AC current function by pressing the DCA or ACA button respectively.

2. Select a range consistent with the expected current or use autorange.

3. Select the front or rear panel input terminals using the

INPUT switch.

4. Connect the signal to be measured to the selected input

terminals as shown in Figure 2-7.

5. Take the reading from the display.

I I

CAUTION: MAXIMUM CONTINUOUS INPUT=3A

_ ._..

~. .-

Settling Time-lsec to within 0.1% of change in reading.

This the specification is for analog circuitry to settle and

does not in&de AID conversion time.

Notes:

1. See paragraph 26.10 for TRMS measurement conSid&

&iOllS.

2. When making TRMS AC voltage measurements below

45Hz, enable the front panel filter modifier to obtain stable readings. A filter value of 10 is recommended.

3. To make low frequency AC mea%uenients in the range

of lOHz to 2oH.z: A. The ACV function must be selected. B. Digital filtering must be used to obtain a stable

reading.

C. Allow enough settling time before taking the reading.

Figure 2-7. Current Measurements

2.8.9 dB Measurements

The dB measurement mode makes it pocisible to compress

a large range of~measurements into a much smaller scope. AC dB measurements can be made with the instrument in the ACV or AC4 function. The relationship between dB and voltage and currentxan be expressed by the followmg equations:

dB = 20 log .%

2-13

At the factory the instrument is set up to be a dBV meter when ACV dB is selected. dBV is defined as deciiels above or below a 1V reference. The instrument will read OdB when

1V is applied to the input. The 1V reference is the factory default reference. With ACA dS selected, the factory default reference is lmA. The inskument will read OdB when lmA is applied to the input.

Reference levels other than 1V and ImA can be established. There are two methods that can be used to establish a dB reference. One method is to use the zero feature. This

simply consists of applying a signal to the instrument and pressing the ZERO button. That suppressed level& the dB reference (OdB point). The alternate method is to utilize the front panel dB program and enter the desired reference

value. An advantage of using the dB program is that-a

source is not needed to establish a reference.

The following procedure explains how to use the zero

feature to establish a reference:

5. ktite,the dB measurement mode by pressing the dB

6. Take the dB reading from the display.

WARNING

With dB enabled, a hazardous voltage baseline

level (~40V or more), not displayed, may be pre-

sent on the input terminals. If not sure what is applied to the input, assume that a hazardous voltage is present.

dBm MeasurementiBm is defined as decibels above or

below a lmW reference. dB~ measurements can be made in

terms of impedance rather than voltage or current. Because the instrument ~cannof directly establish impedance referenws, a v&age reference must be calculated and established for a particular impedance reference. Use the following equation to calculate the voltage refenznce needed for a particular impedance reference:

1. Apply a voltage or current signal, that is to be used~as the dB reference, to the input of the Model 196.

2. Press the ZERO button. The ZERO indicator will turn on and the display will zero. The reference i?now whatever the applied signal is.

3. Disconnect the signal from the instrument.

Program dB allows the user to check or change the dB reference of the instrument. The recommended progmm-

mable voltage reference range is from lOpV to 9.99999v The recommended programmabie current reference range is from lOnA to 9.99999mA. Paragraph 27.77 contains the information needed for using the dB program.

AC dB Measurements-Perform the following steps to make dB measurements:

l. Select the ACV or ACA function.

2. Select the front or rear panel input terminals with the INPUT switch.

3. Check and/or change the dB reference as previously explained.

4. Connect the signal to be measured to the inputs of the

Model 196.

For OdBm, V,., = JlmW l Z.,, Example: Calculate the voltage reference needed to make

dBm measurements referenced to Mx)fi. For OdBm, V,+ = ~O&lOlW :, 6OOQ ..,

= .77456v

Once the necessary voltage reference is known. it canbe established in the Model 196 with the.dB program. Subsequent dBm readings will be referenced to the correspondin impedance reference. Table 2-4 lists the voltage

I erences needed for some commonly used impedance

references.

dBW Measurements-dBW is defined as decibels above or

below a 1W reference. dBW measurements are made in the

same manner as dBm measurements; that is, calculate the

voltage reference for a particular impedance and set the in-

strument to it with the dB program. The only difference between dBm and dBW is the reference point; ZmW vs 1W. The following equation can be used to ca&Jate the voltage reference:

2-14

For OdBW, V,, = dlW*Z,,

Table 2-4. Corresponding Voltage Reference Levels

for Impedance References

Reference Reference

Impedance Impedance

(0 (0

8 50 75

150 300 600

1000

,f for OdBm = -J lO?V*Z,

V V

,*t for OdBW = 4

Reference Voltage

Level for:

OdBm OdBW

0.0894 2;828

0.2236

0.2739

0.3873

0.5477

0.7746

1.0000

ZR,

2.6.10 TRMS Considerations

Most DMMs actually measure the average value of an in-

put waveform but are calibrated to read its RMS equivalent.

This poses no problems as long as the waveform being

measured is a pure, low-distortion sine wave. For complex,

nonsinusodial waveforms, however, measurements made with an averaging type meter can be grossly insccurafe. Because of its TRMS measuring capabilities, the Model 196 provides accurate AC measurements for a wide variety of AC input waveforms.

TRMS Measurement Comparison-The RMS value of a pure sine wave is equal to 0.707 times its peak value. The average value of such a waveform is 0.637 times the peak value. Thus, for an average-responding meter, a correction factor must be designed in. This correction factor, K can be found by dividing the RMS valued by the average vsjue as follows:

K = 0.707 / 0.637

= 1.11

By applying this correction factor to an weraged reading, a typical meter can be designed to give the RMS equivalent. This works fine as long as the waveform is a pure sine, butt the ratios between the RMS and average values of different

waveforms is far from constant, and can vary considerably.

Table 2-5 shows a comparison of common types of

waveforms. For reference, the first waveform is an ordinary sine wave with a peak amplitude of 1OV The average value

of the voltage is 6.37V while its RMS value is ZO7V Jf we apply the 1.11 correction factor to the average reading, its

can be seen thatboth meters will give the same reading,

resulting is no error in the average-type meter reading,

The situation changes with the half-wave rectified sine wave. As before, the peak value of the waveform is IOV, but the average value drops to 3.18V. The R&E value of

this waveform is 5V, but the average responding meter

wiUgiveareadingof35 (3.18xl.l~),~ealingan MOT

of29.4%.

A similar situation exists for the rectified square wave, which has an average value of 5V and an RMS value of 5.CW. The average responding meter gives a TRMS reading of

5.55V (5 x Lll), while the Model 196 gives a TRMS reading of 5V. Other waveform comparisons can be found in Table

2-5.

AC Voltage Offset-The Model 196, at 5%d resolution, will

typically display 150 counts of offset on AC volts with the input shorted. This offset is caused by the offset of the TRMS converter. This offset will not affect reading accuracy and should not be zeroed out using the zero feature. The following equation expresses how this offset (V,,) is added

to the signal input (V,.):

Disp1ayed reading = ’ @‘I=)’ + ‘V,,,)

Example: Range = 2VAC

Offset = I.50 counts (1.5mV) Input = ZOOmV RMS

Display reading = 4 (2OOmV)’ + (1.5mV)

J 0.04v + (2.25 x 10-v)

= .200005V

The offset is seen as the last digit which is not displayed

at5%d resolution. Therefore, the offset is negligible. If the zero feature was used to zero the display, the I50 counts

of offset would be subtracted from Vj. resulting in an error of 150 counts in the displayed reading.

Crest Factor-The crest factor of a waveform is the ratio of its peak value to its RMS value. Thus, the crest factor specifies the dynamic range of a TRMS instrument; For sinusoidal waveforms, the crest is 1.414. For a symmetrical

square wave, the a& factor is unity

The crest factor of other waveforms will, of course, depend on the waveform in question because the ratio of peak to RMS value will vsrj~ For example, the crest factor of a rectang&u pulse is related to its duty cycle; as the duty cycle

~decreases, the crest factor increases. The Model 196 has a

maximum crest factor of 3, which means the instrument will give accurate TRMS measurements of rectangular waveforms with duty cycles as low as 10%.

2-15

BASIC DMM OPERATION

Yaveform

Table 2-5. Comparison of Average and TRMS Meter Readings

,c Coupled

ic Coupled

Peak

Value

RMS

Value

Average

Responding

4&r Reading

TRMS

Meter

Reading

Averaging

Meter

Percent Error

iine

+,p------

la&Wave Rectied Sine

Ul-Wave Rectified Sine

;quare

+10-- --

?I- ~~~

Rectified Square Wave

IOV

1ov

7.07v

5.OOV

7.07v

lO.ow

5.cOv

7.07V

3.53v

7.07v

ll.lOV

5.55v

7.07V

5.oov

7.07v

lO.ooV

5.OOV

29.4%

11%

Triangular Sawtooth

IOV

1ov

,ov l fi

5.77v

ll.lV* q

5.55v

1ov l fi

5.77v

:.11fi-I) x 100

3.6%

BASIC DMM OPERATION

2.6.11 dB Applications

Measuring Circuit Gain/Loss-Any poimin a circuit can

be established as the OdB point. Measurements in that cir-

cuit are then referenced to that point expressed in terms of gain (+dB) or loss (-dB). To set the zero dB point proceed as follows:

1. Place the Model 196 in ACV and dB.

2. Connect the Model 196 to the desired location in then

circuit.

3. Press the ZERO button. The display will read OdB.

4. Gain/loss measurements can now be made referenced

to the OdB point.

Measuring Bandwidth-The Model 196 can be used to determine the bandwidth of an amplifier as follows:

1. Connect a signal generator and a frequency counter to the input of the amplifier.

2. Set the Model 196 to ACV and autorange.

3. Comect the Model 196 to the load of the amplifier.

4. Adjust the frequency of the signsI generator until a peak AC voltage reading is measured on the Model 196. This is the center frequency.

5. Press the dB button and then press the ZERO button. The OdB point is now established.

6. Increase the frequency input~until the Model 196 reads

-3.OOdB. The frequency measured on the frequency

counter is the high-end Emit of the bandwidth.

7. Decrease the frequency input until the dB reading again

falls to -3.OOdB. The frequency measured on the signal generator is the low-end limit of the bandwidth.

Note: The bandwidth of the Model 196 is typically 3oOkHz. Do not use this application to check amplifiers that exceed the bandwidth of the Model 196.

Determining Q-The Q of B tuned circuit~can be deter-

mined as follows:

1. Determine the center frequency and bandwidth as explained in the previous application (Measuring Bandwidth).

2. Calculate Q by using the following formula:

Q ‘= Center Frequency/Bandwidth

2.7 FRONT PANEL PROGRAMS

There are I.7 programs available from the front panel of the Model 196. These ~tiroamms are Listed in Table 26. The following paragraphs describe and explain the operation of each program.

Table 2-6. Front Panel Programs

Program

0 (Menu) Display software level and list

2 (Resolution) 4 (MX+B)

5 (HlILo/Pass)

6 W-9

3O(Save)

31 (IEEE Address)

32 (Line Frequency)

33 (Self Test)

34 (MX+B Parameters;

3.5 (HI/Lo Liits) 36 (Calibration)

37 (Reset)

n Recall status, enable/disable ZERO

FluER dB

Program Selection--Program selection is accomplished by

pressing the PRGM button followed by the button(s) that corresponds to the program number or name. For example, to select Program 31 (IEEE Address), press the PRGM

button and then the “3” and ‘7” buttons.

Data Entry--Program data is applied from the front panel

using the data buttons. The data buttons consist of the but-~

ons~ labeled with the +-oolaritv sipn and numbers 0 through~9.~ Data entry is &bmpl&hed”by pressing the appropriate number button at each cursor location. Cursor location is indicated by the bright, flashing display digit. The cu%or moves one digit to the right every time a number is entered. After entering a number at the least significant

display digit, the cursor will move back to the most significantdiait; Polarity fi button) can be changed with the cmsor at &y display character.‘I’lus (+) is &plied and thus,

not displayed,

Description

available front panel

Programs Change display resolution

(3Yzd, 4%d, 5%d or 6%d). Enable MX+B program. Enable/disable HI/LO/Pass

~ ~%lsaskus, enable/disable ~ multiplexer.

Save currem instrmnent set up.

Recall/modify IEEE address. Recall/modify line frequency setting (50/6OHz). Enter self-test program. Recall/modify MX+B program values. Recalllmodify HI/LO limits. Enter digital calibration mode.

Returns 196 to factory default

conditions.

offset ~comoensation. Recall/modify zero value. RecaWmocbfy falter value. Recall/modify dB reference value.

2-17

Once a program is selected, the following general Mes wiu =PPlY:

1. A displayed program condition can be entered by pressim the ENTER button.

2. P&gram conditions that prompt the user with a flashing digit (cursor) can be modified using the data buttons (0 through 9). Polarity (i button) can be changed with the msor on any character. Plus (+) is implied and thus,

not displayed.

3. Program.5 that contain alternate conditions can be display:d by pressing one of the range buttons. Each

press of one of these buttons toggles the display between the two available conditions.

4. A program will be executed when the pressed ENTER

button causes the instrument to exit the program.

5. A program can be exited at any time and thus not ex-

ecuted, by pressing the PRGM button.

2.7.1 Program 0 (Menu)

1.~ Set the in+ument to the desired fun@iqn and range.

2. Press the PRGM button. The following prompt will be displayed:

PROGRAM ?

3. Enter the number 2 by pressing the “2” button. The current resolution status will then be displayed. For example, if the selected function is currently set for 6% digits of resolution, the following message v+l be displayed:

6% d

4. If an altered resolution is desired, use the manual Range buttons to display the resolution. The V Range button

decreases resolution, while the A Range but&n in-

creases resolution.

5. With the desired resolution displayed, press the ENTER button. The instrument will return to the previously selected function and range.

This program displays the software revision levels of the Model 196 and lists the available front panel progr-. Perform the following steps to use this program:

1. Press the PRGM button. The following prompt-will be displayed:

PROGRAM ?

2. Enter the number 0 by pressing the “0” button. The software level of the instrument will be displayed, For example, if the software level is Bl, the following message will be displayed:

SOFTREV 81

3. Use the manual Range buttons to scroll through the front panel programs. The A range button scmlls forward while the y range button scrolls backward.

4 To exit from the menu, press the PRGM button. The in-

strument will retnrn to the previous operating state.

2.7.2 Program 2 (Resolution)

Program 2 selects the number of display resolution digits. The resolution available is dependent on function and range. Table 2-7 lists the display resolution availabie for the various function/range combinations. Display resolution can be set for each function and is remembered by each function as long as the instrument remains powered up. Resolution can be remembered after power-down by running Program 30 (Save). To change the display resolution, perform the following procedure:

Table 2-7. Display Resolution

Available

Function Range

DCV All

ACV AU

DCA IAll

I AcA I-

Resolution

31/2d, 4%d, 5Hd, 61hd

3%d, 4%d, 5%d

( 3%d, 4%d, 5Yzd I

3%d, 4Hd, Shd

2.7.3 Program 4 (MX+B)

This program allow3 the operator to automatically multiply normal display readings (X) by a constant (M) and add a constant (B). The result (Y) will be &played in accordance with the formula, Y=MX + B. This program is useful when slope calculations are required for a series of measurements.

The values of M and B can be char& by utilizing Pro-

gram 34. Perform the following steps to enable the MX t B feature:

1. Set the Model 196 to the desired function and range.

2. Connect the signal to be measured (x) tvthe input of the Model 196.

2-16

BASIC DMM OPERATION

3. If the values of M and B need to be checked or changed, do so using Program 34.

4. Press the PRGM button. The following prompt will be

displayed:

PROGRAM ?

5. Enter the number 4 by pressing the “4” button. The cur-

rent status of the MX+B program will be displayed. For

example, if the MX+B is currently disabled, the follow-

ing message will be displayed:

MX+B OFF

6. Any range button will to&e the display to the alternate

MX+B status. Therefore, press a Range button and the

following message will be displayed:

MX+B ON

7. With the message “MX+B ON” displayed, press the ENTER button to enable MX+B. The ins&rnent will return to the function initially set.

8. AU subsequent readings cr) wiJ.l be the result of the equation: Y=MX+B.

Notes:

Table 2-8. Example MX + B Readings

lzooomc

~-2.5OOOOvDc

14.4500OVAC

11.00000kQ

*where M = +1.5 and B = +5.

2.7.4 Program 5 (HI/LO/Pass)

Program 5 is used to enable the HI/LO/PASS program. With this program, the Model 196 will indicate whether or not a specific reading falls within a prescribed range. The factory defa&L.Q limit is a negative full scale reading, with the actual value depende~ntron function and range. Conversely, the factory’default y limit is a positive full scale reading. With these f full scale limits, the Model 196 will display the HI or Lo message for overrange readings and the PASS message for oh-range readings. The HI and LO limits can be set to any on-range value with Program.35 (HI/Lo Limits).

1. The hIX+B feature can be disabled by again running Program 4. While in the progxwn, press a range button until the message “MX+B OFF” is displayed and then press the ENTER button.

2. Once h4X+B has been enabled, the Model 196 will show the value of Y. If the value of Y is larger than can be handled by the particular range, the overrange message will be displayed, indicating the instrument must beswitched to a higher range.

3. User selected values of M and B will be stored within the Model 196 until the power is turned off (unless saved by Program 30). These constants will be used whenever, X+B is enabled. Note however, that the value of B is scaled according to the range in use. Example: A value of 19.00000 entered for B is actually 19.0000OV with the instrument on the 30V range and 19O.OOOOV with the instrument on the 3OO.oMxxT range.

4.An example of readings that will be obtained when MX+B is enabled is shown in Table 2-8. Each of the obtained values for Y assumes the following constants: M=+1.5; B=+5.

This feature is especially useful for component evaluation, where certain component tolerances must be observed. Once the limits are programmed into~ the instrument, the operator need only monitor the display messages to determine the integrity of the device. perform the following proceduIe to enable Program 5:

1. Select the desired function and range, and zero the inshument, if desired. These operating parameters can-

not be changed once the program is active without exiting the program.

2. If the limits need to be checked or changed, do so using Program 35.

3. Press the PRGM button. The following prompt will be displayed:

PROGRAM ?

4. Enter the number 5 by pressing the “5” button. The

following message will be displayed briefly:

HI LO PAS5

2-19

BASIC DMM OPERATION

5. At this point, the instrument will run the program. No

numeric readings wilI be displayed. Instead, one of the following messages will be displayed:

A. If the measured value is less than the low limit, the

following message will be displayed:

B. If the measured value is greater than the Mgh limit,

the following message will be displayed:

C. If the measured value falls within the high and low

limits, the following message will be displayed:

PASS

6. To disable the program, press the function button that has the indicator light on. This will disable the~prZ@am without changing the measurement parameters (i.e. function, range, etc.) of the instrument.

Notes:

1. L&its can be set using Program 35 with or without Program 5 enabled.

2. User selectable values of L and H will be stored within the Model 196 until the power is turned off (unless saved

by Program 30). These constants will be used whenever

HI/LO/PASS is enabled. Note however, that the value of L and H are scaled according to the range in use.

3. Pressing any ofthe front panel controls, &cept dB (unless in AC), ENTER, and LOCAL, will disable the program and select the feature associated with that button.

~~~~ ~~~ >)

MUX ON

3. If the alternate multiplexer status is desired, press one of the range buttons. The alternate status will be displayed as follows:

MUX OFF

4. To enter the displayed multiplexer status, press the

VENTER button. The instrument will return to the

previous operating state.

NOTE

with the auto/Cal multiplexer disabled, the internal zero and calibration are affected by changing the nominal inout level. esneciallv on ohms and the 3OOVDC range. WheneGer the’applied input level changes, press the selected function button to perform an auto/Cal routine, otherwise substantial errors will result. Zero and calibration may also be affected by time. Thus, it is recommended that the selected function button be pressed periodically.

2.7.6 Program 3O~(Save)

Program 30 saves current instrument conditions set up by the user. These user programmed conditions will then replace the previously saved default conditions on power

up. Also, an SDC or DCL asserted over the IEEE-488 bus

will return the instrument to these saved conditions.

The following instrument operating parameters are saved by this program:

2.7.5 Program 6 (Multiplexer, Auto/Cal)

The multiplexer autoical routines may be defeated by run-~

ning Program 6. Using the Model 196 with the auto zerokal defeated increases measurement speed and is useful for making high impedance DC voltage measurements which can be affected by the input multiplexing. Perform the

following steps to run this program:

1. Press the PRGM button. The following prompt will be displayed:

PROGRAM ?

2. Enter the number 6 by pressing the “6”button. The current multiplexer status will then be displayed. For example, if the multiplexer is on, the following message~~* be displayed: ~;~

2-20

Function Range

Resolution Zero status (on/off) and value Filter status (on/off) and value ACdB status (on/off) and reference value

IEEE ~address ~.~

Line frequency setting MX+B status (on/off) and values HI&O limits Ohms compensation status (on/off)

Perform the following procedure to use the save program:

1.~ Seth up the instrument as desired or~run Program 37 (Reset) to return the instrument to the factory default

conditions.

BASIC DMM OPERATION

2. Press the PRGM button. The following prompt will be displayed:

PROGRAM ?

3. Enter the number 30 by pressin the “3” and “0” buttons. The following message & be displayed briefly:

SAVE

4. The following message will then be displayed:

ENTBR?

5. To save the instrument set up conditions, press the ENTER button. The following message v$k~displayed

L..z^cL..

BNTBRBD

6. The instrument wi!.l return to the conditions set up in step 1 and will now power up to those conditions.

Notes:

1. TO exit the program without changing the previous

default conditions, press any front panel button except the ENTBR button. The instrument will return to the operating states set up in step 1.

2. To return the instmment to the factory power up default conditions, use Program 37 (Reset) and save the conditions using Program 30.

3. When using this program, make sure that the rest~of the instrument is in the desired operating state.

2.7.7 Program 31 (IEEE Address)

Program 31 allow? the user to check and/or modify the ad-

dress of the IEEE&B interface. The interface can be set to

address from 0 to 30 Detailed information on

bus rs prowded m Section 3. Perform the

!!Zo%g%ps to use this program:

1. Press the PRGM button. The following prompt will be

displayeyed:

PROGRAM ?

2. Enter the number 31 by pressing the “3” and “1” buttons. The IEEE address value will be displayed. Exampie: If the current primary address of the instrument is 7, the following message will :be displayed:

3. Ifit is desired to retain the displayed status value, proceed to~step 4. To change the status value, enter the address

number (0 to 30).

4. With a valid status disulaved, mess the ENTER button. The instrument will %rn to the previously defined

,stam

Notes:

1. If an invalid number is entered, the instrument wiIl exit zrn@t$ program with the IEEE primary address being

2.To change the default address of the instrument, select the desired IEEE address using this program and then

Program 30 (or Ll over the IEEE bus) to save it. Cvchng

power, Program 37 (Reset), or an SDC, DCL or Lb sen? over the bus will not have any affect on the new default address.

3. If the JEBE address is changed but not saved:

A. 2 cl&power will return the insmument to the default

B .

B. Program 37 (Reset), or an SDC or DCL sent over the

bus wiB not have any affect on the current address.

C. Sending LO over the bus will not change the current

IEEE address, and will save that address as the power

up default address.

4, An /mCAfJ’ error d default the IEEE address to 7 and

the line frequency setting to 6OHz.

~~ 2,7.8 Program 32 (Lht? Frequency)

The Model I.96 does not automatically detect the power line

frequency upon power up.~~This program aLlows the user to check the line frequency set to select the alternate fmquenc$K&%e&Z%Z~~~ to either 5OH.z or 6oHz. Perform the folloxjng steps to check

and/or change the line frequencysetting of the yodel 196.

1. Press the PRGM button. The following prompt will be displayed.

PROGRAM ?

2. Enter the number 32 by pressing the “3” and “2” buttons. The current line frequency setting will then be

displayed. J.f the instrument is currently set to 6OH.2, the

following message @I be displayed:

PRBQ=6OHz

07 IE

2-21

BASIC DMM OPERATION

3. If the displayed frequency setting matches the available line frequency, proceed to step 4. If the alternative line frequency setting is needed, press one of the Range but-

tons. The display will toggle to the alternate frequency

setting as shown:

FREQ=5OHz

4. With the correct frequency setting displayed, press the

FJITER button. The instrument will return to the previous operating state.

Notes:

1. To change the default line frequency setting of the ins&~ment, select the desired setting using this prog;&% and then Program 30 (or Ll over the IFEE bus) to save it. Cycling power, Program 37 (Reset), or an SDC, DCL or I.0

sent over the bus will not have any affect on the new default setting.

2. If the line frequency setting is changed but not saved: A. Cycling power, x~r sending an SDC~or DCL over the

bus will return the instrument to the default.s&&.

8. Program 37 (Reset) will not have any affect on the cur-

rent setting.

C. Sending Lo over the bus will not change the current

line frequency setting, and will save that setting as the default setting.

3. An “UNCAE’ error will default the IEEE address to 7 and the line frequency setting to 6OHz.

2.7.9 Program 33 (Diagnostic)

Program 33 is a diagnostic program designed to switch on tious switching PET’s, relays and logic levels to allow signal tracing through the instrument. Also, tests on the display and memcry are performed. Refer to paragraph 6.7.3 in the maintenance section to use this program to troubleshoot the instrument.

2. Enter the number 31 by pressing the “3” and ‘+I” buttons. The current value of M will now be diip1ayed.X thefactory default value is the current value of M, then the following message will be-displayed:

l.OLlONO M

3. If it is desired to retain the displayed M value, proceed to step 4. If it is desired to modify the M value, do so

causing the data buttons. Note that valid M values are in

the range of -9.999999 to +9.999999.

4. With a M value displayed, press the ENTER button.

5. The ctit%t~B value will now be displayed. If the factory defualt~value is the current B value, the following message will be displayed:

0000.000 B

Decimal point~position is determined by the mnge that

the instrument was on when t&s program was selected.

6. If it is desired to retain the displayed B value, proceed to step Z If it is desired to modify the value of M, do so usin

fmm f

7. With a valid B value displayed, press the ENTER button. The instrument will return to the previously defmed state of operation.

Notes:

1. User se&ted &&s of M and B will be~st&ed &thin the Model 196 until the power is turnedoff (unless saved by Program 30). These constants will be used whenever MX+B is enabled. Note however, that the value of B is

scaled according to the range in use. Example: A value of 19.00000 entered for B is actually 19.O0XOV with the instrument on the 3OV range and 19O.OOC0V with the instrument in the 300V range.

2. The user can set the values for M and B as the power

up default values by running Program 30.

the data keys. Notes that the B value range is

.ooolxlo-~ to i9999.999 (in&ding zero).

2.7.10 Program 34 (MX+B Parameters)

This prqpm allows the operator to check/change the M and B values for the MX+B feature (Program 4) of the Model 196. The factory lBOOOOO and the value of i. values of M and B, proceed as follows:

1. Press the PRGM button. The following prompt will be displayed:

2-22

ower up default value of M is

1s OOOOCKX. To check/change the

PRO&AM ?

2.7.11 Program 35 (Hi/LO Limits)

Program 35 is used to set the high and low limits for t& HI/LO/PASS program (l’rogram 5). The fa~ctory default limits are +303X03 counts (Hl limit) and -3030300 counts (LO limit). The actual value of the limits is dependent on the range. For example, the factory default HI limit on the 3V ran e is 3.03OOoW, while the factory default HI limit ori the3c8 to~set HI and Lo limits:

range 1s 30.3ooo(N. Perform the following procedure

BASIC DMM OPERATION

1. Place the Model 196 in the function and range that the HI/LO/PASS program (Program 5) will be used.

2. Press the PRGM button. The folIowing prompt will be displayed:

PROGRAM ?

3. Enter the number 35 by pressing the “3” and “5” buttons. The current LO limit wiII be displayed. For example, if the I.0 limit is the factory default value, the following message will be displayed:

-303.0000 Lo

Decimal point position is determined by the range that the instrumentwas on when this program was selected.

4. If it is desired to retain the dis to step 5. Otherwise, modify t

layed LO limit, proceed

e &splayed value using

the data buttons. The IO limit must be in the range of

-3030000 to +3030000 counts.

5. With the desired LO lit displayed, press the ENTFR button. The current HI limit will be~dis la ed. For ex-

ample, if the LO lit is the factory d &I? a t value, the

following message will be displayed:

303.0000 HI

Decimal point position is determined by the ran e that the instrument was on when this program was se e&d.

6. If it is desired to retain the displayed HI limit, proceed to step 7. Otherwise, modify the displayed value using the data buttons. The HI limit must be in the~range of

-3030000 to +3030ooo counts.

7. With the desired HI limit displayed, press the ENTER

button. The instrument will return to the previous operating state.

2.7.12 Program 36 (Calibration)

The user can easiIy perform front panel digital calibration by applying accurate calibration signals using Program 36. The calibration signals can be either prompted default values or numbers entered from the front panel. Paragraph

6.4.5 descriis the basic steps for using this program, while paragraphs 6.4.7 through 6.4.12 provide the complete front panel calibration procedure.

2.7.13 Program 37 (Reset)

Program 37 resets instrument set up parameters back to factory default conditions. The factory default conditions are

listed in Tables 2-l and 3-T’. Perform the following steps to

run this program.

1. Press the PRGM button. The following prompt will be displayed:

PROGRAM ?

2. Enter the number 37 by pressing the “3” and “7” buttons. The following message will be displayed briefly:

RESET

3. The following promptwill then be displayed:

4. Press the ENTER button. The following message will be displayed briefly and the instrument~will return to the factory default conditions.

ENTERED

Notes:

1. Userselected limits wiil be stored in the Model.196 until power is turned off (unless saved by Program 30). These constants will be used whenever Program 5

@I/IAX?~SS) is enabled.

2. Limits set by the user will become the power up default limits by

running Program 30 (Save).

3. Entering an invalid value will result with the instrument using the power up default limit.

Notes:

1. Prwgram 37 (Reset) can be aborted by pressing any front panel button, except the ENTER button, when the prompt “ENTER?” is displayed. The instrument will return to the previous operating state.

2. Once the instrument is reset to the factory default con-

ditions with this program, Program 30 must be run if it is desired to have the factory default conditions on subsequent power ups.

3. Program 37 (Reset) will have no aifect on the current ISEE

address and line frequency setting.

2-23

SASIC DMM OPERATION

2.7.14 Program L!

The ohms offset compensation program is used to compen-

sate for voltage potentials (such as thermal EMFs) across the resistance to be measured. This feat&s can be used for both 2-terminal and 4-terminal resistor measurements up to 3OkR. Additional information on ohms offset compensation can be found in paragraph 2.6.6. Perform the following steps to use the ohms offset compensatron program:

1. Press the PRGM button. The following prompt wilJ be

displayed:

PROGRAM ?

2. Press the Q button. The current status of ohms compensation wiIl be dis is currently displayed:

3. If the alternate status is desired ,gressoneoftheRange buttons. The alternate status will

4 With the desired compensation status displayed, press

the ENTER button. A. If ohms offset compensation was enabled, the instru-

ment will be placed in the ohms function with the 0 indicator light flashing.

B. If ohms offset compensation was disabled, the insnu-

ment will return to the previous 0 the ohms function is selected, K .’ will not flash.

layed. For example, if compensation

disa

led, the following messages will bee

COMPOFF

e displayed as fo!.lows:

COME’ ON

eraling state. When

e B mdrcator light

the ranges. Example: If 1V DC is set to the zero value of the 3V DC range, the zero value in the program wiil be

displayed as 1.000000. On the 30V DC range the zero value will still be 1V DC, but will be expressed as 01.00000 in the program.

Perform the following procedure to implement Program ZERO.

1. Press the PRGM button. The following prompt will be

displayed:

PROGRAM ?

2. Press the ZERO button. The current zero value will then be displayed. Example: If the instrument is on the 3OV DC range and the current zero value is +3V DC the following message will be displayed:

03.00000 z

3. If it is desired to retain the displayed zero value, press the ENTER button. The instrument will return to the

previous operating state with the zero modifier enabled. The displayed reading will reflect the entered zero value.

4. To modifythe zero value, enter the new value and press the ENTER button. The instrument will return to the previously defined state with the zero modifier enabled using the newly entered zero value.

Note: The factory default power up zero value is OCKKICO.

If it is desired to have a different zero value displayed

on power up, modify the zero value using Program

ZERO followed by Program 30 to save it.

Notes:

1. The lT iridicator~light reveals the status of ohms offset compensation. With the ohms function selected, a

flashing 0 light indicates that compensation is enabled, and conversely, a non-flashing Q light indicates that compensation is disabled.

2. The status of ohms offset compensation can be saved as a power up default condition by running Program 30.

2.7.15 Program ZERO

Program ZERO allows the user to check or modify the,,zero value. A complete explanation of the zero modifier can be found in paragraph 2.6.2. Once a zero v&e is set on a measurement function, that zero level is the same on all

2-24

2.7.16 Program FILTER

Program FILTER allows the user to modjfy~ the weighting of the digital filter. Valid filter values are from 1 to 99. More information concerning the filter can be found in paragraph

2.6.3.

Perform the following steps to check and/or modify the filter value.

1. Select the desired function.

2. Press the PRGM button. The following prompt will be displayed:

PROGRAM ?

BASIC DMM OPERATION

3. Press the FIITER button. The current filter value will then be displayed. Example: If the filter value is 5, the follow-

ing message wilI be displayed:

05 F

4. If it is desired to retain the displayed filter value, pro-

ceed to step 5. If it is desired to modify the filtervalue, do so using the data buttons.

5. With the desired filter value displayed, press the ENTER

button. The instrument will return to the previously defined state when the filter is enabled.

6. To check or change the filter value of another function, select the function and repeat steps 2 through 5.

Notes: l.The factory default power up filter value is 10. If it is

desired to have a different filter value on power up, change the filter value using Program FILTER followed by Program 30 to save it.

2. Entering a filter value of 00 wilI default the filter value back to the previous value and return the instrum~ent~to the previously defined state with the filter disabled.

2.7.17 Program dB

referencepn power up, modify the reference using Pro-

gram dB followed by Program 30 to save it.

2.8 FRONT PANEL TRIGGERING

With the instrument properly configured over the IEEE-488 bus, readings can be triggered from the front panel using

the ENTER button. The following paragraphs provide general procedures for one-shot front panel triggering and front panel triggering into data store.

NOTE

The procedures in this section require IEEE-488 bus programming. Refer to Section 3 particukxly paragraphs 3.9.7 (Triggering) and 3.9.9 (Data Store) fx$t& on progrsmming the instrument over the

On power up, the instrument is in the continuous trigger mode with the conversion rate determined by the internal time base. To press of the Ed OR button wilI trigger one reading, perform the following general procedure:

lace the instrument in a state where each

XJTE

Program dB allowsthe user to check and/or modify~the dB reference. The programmable voltage reference can be up to 9999999V and the be up to 9.99Y999mA. ?I ments is provided in paragraph 2.6.9. Perform the following steps to use this program:

1. Press the PRGM button. The following promptwiIl be displayed:

2. Press the dB button. The current reference level will be displayed. Example: If the reference is 1V or lmA, the following message wilI be displayed:

3. Modify, if desired, the dB reference level and press the ENTER button. The recommended reference mnge is lo/# to 9.999999V and l!lnA to 9999999mA. The ins&u-~ ment wilI return to the previously defined state.

Note: The factory default power up voltage reference is

1.OOOOOOV with the instrument in ACV and 1M)OOOOmA with ACA selected. If it is desired, to have a~ different

rogr-able current references can

et&d information on dB messure-

PROGRAM ?

1.oocmoodB

ENTERED

1. ~Place the instrument in the desired function and range.

2. mace the instrument in “one-shot on external trigger” by sending ‘I7 over the IEEE-488 bus.

3. Press the LOCAL button to return control to the front pill-d.

4. Each press of the ENTER button will trigger one reading.

2.8.2 Triggering Readings into Data Store

The front panel ENTER button can be used to trigger reading into data store. In the one-shot trigger mode, each

ress of the ENTERbutton wilI store one readin

uffer In the continuous trigger mode, the ENTE

E will start the storage process at the rate that was programmed over the IEEE-488 bus. Performthe following general procedure to trigger readings into data store from the front panel:

1. Place the instrument in the desired function and range.

2. place the instrument in the appropriate trigger mode: A. To store one reading in the buffer after each press of

the ENTER button, send T7 (one-shot on external trigger) over the bus.

B. To store a series of readings in the buffer after the

ENTER button is pressed, send~T6~(continuous on CCternal trigger) over the bus.

in the

button

2-25

3. Configure the storage interval and buffer size of the data store by sending the appropriate Qn and I commands

over the bus (see paragraph 3.9.9).

4. Press the LOCAL button to return control to the front panel.

5. Press the ENTER key to either store one reading in the buffer or to start storage of a series of readings.

2.9 EXTERNAL TRIGGERING

The Model 1% has two external BNC connectors on the

rear panel associated with instrument triggerinp. The EXTERNAL TRIGGER IiWUT connector allows the instrument to be triggered by other devices, while the

VOLTMETER COMPLETE OUTPUT connector allows the

instrument to triggerother devices.

2.9.1 External Trigger

The Model 196 may be triggered on a continous~ or oneshot basis. For each of these modes, the trigger stimulus

will depend on the selected trigger mode. In the continuous

trigger mode, the instrument takes a continuous series of readings. In the one-shot mode, only a single reading is taken each time the instrument is triggered.

The external trigger input requires a fallin ‘ITL logic levels, as shown in Figure 2-8.

edge pulse at

Ebb omaections to

the rear nanel !?XTERNAL TRIGGER INPUT iack should

be made with a standard BNC connector. If thei&rument

is in the external trigger mode, it will be triggered to take readings while in either a continuous or one-shot mode when the negative-going edge of the external trigger pulse, OCCUIS.

To use the external trigger, proceed as follows:

1. Connect the external trigger soum to the rear panel BNC EXTERNAL TRIGGER INPUT ccinnector. The shield

(outer) part of the connector is connected to digital common. Since an internal pull-u ~re.?.istor is used, a mechanical switch ma be used.

ate however that de-

bcmncing circuitry wiEyprobably l! required to avoid im-

proper &&e&g.

CAUTION Dq not exceed 30V between digital common and chassis ground, or instrument damage may

occur.

2. Place the instrument in the “one-shot on external trigger” (T7) or “continuous on external trigger’ (T6) as explained in paragraph 3.9.7.

3. To trigger the instrument, apply a pulse to the external trigger input. The instrument twill process a single reading each time the pulse is applied (one-shot), or start a continuous series of readings.

Note: External triggering can be used to control the fill rate in the data store mode with the data store enabled and one-

shot mode selected, each trigger will cause a reading to be

stored.

2.9.2 Voltmeter Complete

The Model 196 has an available output pulse that can be

used to trigger other instrumentaticm. A single TTL

compatible negative-going pulse (see Figure 2-9) will ap-

pear at the VOLTMETER

COMPLETE OUTPUT jack each

time the instrument completes a reading. To use the

voltmeter complete output, proceed as follows:

TRIGGERS ON

LEADING EDGE

Figure 2-8. External Trigger Pulse Specifications

2-26

1. Cmnect the Model 196 to the instrument to be triggered with a suitable shielded cable. Use a standard BNC con-

nector to make the connection to the Model 196.

CAUTION Do not exceed 30V between the VOLTMETER COMPLETE common (outer ring) and chassis ground or instrument damage may occur.

BASIC DMM OPERATION

2. Select the desired function, range, trigger mode, and other operating parseters, as desired.

3. In a continuous trigger mode, the ins@unent will out-

put pulses at the conversion rate; each pulse will occur after the Model I% has completed a conversion.

4. In a one-shot trigger mode, the Model 196 will output a pulse

once each time it is higgered.

REA?&JG BEGIN NEXT

LS TTL LOU 1

(025V TYPICAL)

I I

CONVERSION

1’

Figure 2-9. Voltmeter Complete Pulse

Specifications

Figure 2$X Uses shielded cables with BNC connectors. The Model 196~YOLTMETER coMrmouTr~jack should be connected to the Model 705 EXTERNAL TRIG

GER INPUT jack. The Model 196 EXTEXNALTRIGGEE INPUT jack should be connected to the Model 7Ki CHANNEL READY OUTPUT. Additional connections,

which are not shown on the diagram, will also be necessary to apply signal inputs to the scanner cards,

~~~

as well as for the signal lines between the wanner and the Model 196.

2. Place the Model 196 in “one-shot on external trigge~” 0 as explained in paragraph 3.9.7.

3. Program the Model 705 scan parameters such as first and last channel as required. Place the instrument in the single scan mode.

4. lnstdl the desired scanner cards and make the re input and output signal connections. See the MO Instruction Manual for details.,

5. Begin the measurement sequence by pressing the Model 705 START/STOP button. The Model 705 will close the first channel and trigger the Model 196 t0 t&e a reading.

When the Model 196 completes the reading, it will hig-

ger the Model 705 to go to the next channel. The pro-

cess repeats until all programmed channels have been

scanned.

uired

i el705

2.9.3 Triggering Example

As an example of using both the external trigger input and the meter complete output, assume that the Model 196 is

to be used in conjunction with a Keithley Model 705 Scanner to allow the Model 196 to measure a number of different signals, which are to be switched by the scanner. The Model 705 can switch up to 20 2-pole channels (20 singlepole channels with special cards such as the low-current card). In this manner, a single Model 196 could monitor up to 20 measurement points.

By connecting’the triggering inputs of the two instruments L__..,- ~~~

cogerner, a complete automatic measurement sequence” could be performed. Data obtained from each measurement point could be stored using the data store of the Model 196.

Once the Model 705 is programmed for its scan sequence, the measurement procedure is set to begin. When the

Model 705 closes the selected channel, it triggers the Model

705 to scan to the next channel. The process repeats until all channels have been scanned.

To use the Model 1% with the Model 705, proceed as

follows:

MOOEL 705

MODEL 196

I /I

1. Connect the Model 196 to the Model 705 as shown in

Figure 2-10. External Triggering Example

2-271248

SECTION 3

IEEE-488 PROGRAMMING

3.1 INTRODUCTION

This section contains information on programming the Model 196 over the IEEE-488 bus. Detailedinstructions fork all programmable functions are included; however, information concerning operating modes presented elsewhere is not repeated here.

Additional IEEE-488 information is provided in the following appendices:

Appendix A-ASCII character codes and multiline interface command messages.

Appendix B-Progmmning information for using the FM

PC/XT computer with the Model 8573A interface. Appendix C-Saniple programs using a variety of ef!rent

controllers with the Model 196. Appendix D-A detailed overview of the IEEE488 bus.

Also, a tear out card listing the device-dependent commands follows the appendices.

S&ion 3 contains the following infonnation:~ ~_~~~ ~:

3.7

3.8

3.9~

3.10

3.11

Front Panel Aspects of- IEEE-488 Operation:

Describes the operation of the LOCAL key and bus status indicators, and summarizes front panel messages that may occur during bus operation.

General Bus Command Programming: Outlines methods for sendingg&&al bus commands to the instrument.

Device-Dependent Commands: Contains descrip-~ tions of most of the programmjng commands used to control the instrument over the bus.

Using the Translator Mode: Describes an alternate

naming method of using easily recognized

Prow user-defined words in place of device-dependent

xommands.

Bus Data Transmission Times: Lists typical times when accessing instrument data over the bus.

3.2 A SHORT-CUT TO IEEE-488 OPERATION

The paragraphs below will take you through a step-by-step

procedure to get your Model 196 on the bus as quickly as possible and program basic operating modes. Refer to the remainder of S&ion 3 for detailed information on IEEE-488 operation and programming.

3.2

3.3

34 Interface Function Codes: Defies IEEE standard

3.5 Primary Address Selection: Tells how to program

3.6 Controller Programming: Demonstrates simple

A Short-cut to IEEE-488 Operation: Gives a

simple step-by-step procedure for g+ng on the bus as quickly as possible.

Bus Connections: Shows typical methods for connecting the instrument to the bus.

codes that apply to the instrument.

the instrument for the correct primary address.

programming techniques for a typical IEEE-488 controller.

Step 1: Connect Your Model I96 to the Controller

With power off, connect the Model 196 to the IEEE-488 in-

terface of the controller using a standard interface cable. Some controllers such as the HI-85 include an integral cable, while others require a separate cable. Paragraph 3.3 discusses bus connections in more detail.

Step 2: Select the Primary Address

Much like your home address, the primary address is a way

for the controller to refer to each device on the bus individually. Consequently, the primary addres~s of your

Model 196 (and any other devices on the bus, for that mat-

3-l

IEEE-488 PROGRAMMING

ter), must be the same as the primary address specified in the controlletis programming language, or you will not be able to program instrument operating modes and obtain data over the bus. Keep in mind that each device on the bus must have a different primary address.

The primary address of your Model 196 is set to 7 at the

factory, but you can program other values between 0 and 30 by pressing PRGM, 3, 1, and then using the data en* keys to change the primary address. Once the desired value is displayed, press ENTER to program the value.

More detailed information on primary address selection is located in paragraph 3.5.

Step 3: Write Your Program

Even the most basic operations will require that you write

a simple program to send commands and read back data from the instrument. Figure 3-l shows a basic flow chart that a typical simple program will follow. The programming example below follows this general sequence. This program will allow you to type in command strings to program the instrument and display data on the computer CRT.

HP85 Progra below to send programming commands to the Model 196

and display the data string on the computer CRT.

PROGRAM COMMENTS

10 REMOTE 707

26 DISP L L COMMAND’ ’ j Prompt for command 30 INPUT CB

40 UUTPUT707; CB

50ENTER707; A$

60 DISP A8

70 GOTO 20

80 END

mming Example-Use the simple program

Send remote enable.

string. Input the command string. Send command string to

196

Get a r&ding from the inshument.

~Diiplay the reading.

Repeat.

OPERATING

REQUEST DATA

END

3-2

Step 4: Pmgram Model I.96 Operating Modes Step 5: Get Readings from the Model I96

You can program instrument operating modes by sending Usually, you will want to obtain one or more readings from the appropriate command, which is made up of an ASCII letter representing the command, followed by one or two

the Model 196. In the example program abcwe, a single

reading is requested and displayed after each command. numeric parameters separated by commas for the corn-~ In other cases, you may wish to program the instrument mand option. Table 3-l summarizes the commands used

configuration& the beginning of your program, and then

to select function and range. obtain a whole series of measurements.

A number of commands can be grouped together in one The basic reading string that the Model 196 sends over the string, if desired. Also, you must terminate the command bus is in ASCII characters of the form: or command string with the X character in order for the instrument to execute the commands in question. NDCV-l234567E+O

If you are using the programming example from Step 3 where: N indicates a normal reading (0 tiould indicate an above, simply type in the command string when prompted overflow), to do so. Some example strings are given below. DCV shows the function in effect (in this case, DCV)

-1.234567 is the mantissa of the reading data,

E?-0~ represents the exponent.

F3X: select DCA function. FORZX: select DCV function, 3V range.

Table 3-1. IEEE-488 Commands Used to Select Function and Range

:ommand I

FO Fl

Execute other device-dep$w~commands.

DC volts AC volts ohms

DC current

AC current E F6 F7

ACV dB

ACA dB

Offset compensated ohm.~~-

WY Aa’ ~~!lF!K

ACA Ohms ACV dB, &CA dB Ohms

Auto Auto Auto Auto Auto Auto Auto Auto

300mV 3oOmV 3OOfi 300~2% 300 0 Auto Auto 300 I-i E R3 R4 R5

3v 3v 3mA 3mA 3k0 Auto Auto 3kt-l

30 V 30 V 3OmA 30mA 30 kQ Auto Auto 3Ok’2 300 v 300 v 3oomA 3ooti-TLiO~kQ Auto A&o 30 lit-l 300 V 300 V 3 A 3 A 3Mfl Auto Auto 30 kfl 300 V 300 V 3 A 3 A 3OM!l Auto Auto 30 kQ

300 V 300 V 3 A 3 A 3OOMfl Auto Auto 30, kQ

Offset Compensated

3-3

3.3 BUS CONNECTIONS

The Model 196 is intended to be connected to the IEEE-488 bus through a cable equipped with standard IEEE-488 connectors, an example of which is shown in Figure 3-2. The connector is designed to be stacked to allow a number of parallel connections at one instrument;~~Two screws are located on each connector to ensure that connections remain secure. Current standards call for metric threads, which are identified with dark colored screws. Earlier versions had different screw& which were silver colored. Do not attempt to use these type~~of connectors tin the Model 196, which is~aesigned for metric threads.

Figure 3-2. IEEE-488 Connector

A typical connecting scheme for a multiple-instrument test set up is shown in Figure 33. Although any number of connectors can be stacked on one instrument, it is recommended that you stack no more than three connectors on any one unit to avoid possible mechanical damage.

INSTRWENT

INSTRUMENT

CONTROLLER

Figure 3-3. IEEE-488 Connections

Connect the Model 196 to the IEEE-488 bus as follows:

1. Lime up thecable connector with the connector located on the rear panel of the instrument. The connector is designed so that it will fit only one way. Figure 3-4 shows the location of the IEEE-488 connector on the instrument.

2. lighten the saew securely, but do not overtighten them.

3. Add additional connectors from other instruments, as required.

4. Make certain that the other end of the cable is properly connected to the controller. Most controllers are equipped with an IEEE-488 style connector, but a few may require a different~ type of connecting cable. Consult the instruction manual for your controller for the proper connectmg metnoa.

. . _..

3-4

ADDRES3ENTEREDWiTH

FRONT PANEL PROGRAM 31

FIgure 3-4. IEEE-488 Connector Location

NOTE

The FEE-488 bus is limited to a maximum of 35

devices, incluiing the controller. The maximum

cable length is 20 meters, or 2 meters times the number of devices, which ever is less. Failure to observe these limits may result in erratic bus operation.

IEEE-488 PROGRAMMING

Table 3-2. IEEE Contact Designation

contact IEEE-488

Number Designation

1 DIOl

D102

;

D103

DI04

7 N-RFD

NDAC

i lo 11 ATN

SHIELD

DI05

14 D106

D107

DI08 17 l8

19 20 Gnd, (8)*

Gnd, (9)

Gnd, (lo)*

23 Gnd, (ll)* 24 Gnd. LOGIC

Tyge Data

Data Data Data Management Handshake Handshake Handshake Management Management Management Ground Data Data Data Data

Management

Ground Giounii Ground Ground Ground Ground Ground

Custom cables may be constructed by using the informa-

fiOn in Table 3-2 and Figure 3-5. Bble 3-2 Ii& the COntad

assignments for the bus, and Figure 3-5 shows the contact

CAUTION

IEEE-488 common is connected to chassis ground and cannot be floated.

CONTACT 12

CONTACT 241

-7 r

I \

CONTACT I

L CONTACT 13

Figure 3-5. Contact Assignments

*Numbersin parentheses refer to signal ground rehrn

of reference-d contact number. EOI and REN signal

lines return On contact 24.

3.4 INTERFACE FUNCTION CODES

The interface function codes, which are part of the IEEE-488

standards, define an instmment’s ability to support various

interface functions, and they should not be confused with programming commands found elsewhere in this manual. Interface function codes for the Model 196 are listed in Table 3-3 and are listed for convenience on the rear panel adjacent to the IEEE488 connector. The codes define Model 196 capabilities as follows:

SH (Source Handshake)-SHl defines the ability of the Model 196 to properly handshake data or command bytes when the unit is acting as a source.

AH (Acceptor Handshake&AH1 defines the ability of the Model 196 to properly handshake the bus when it is acting as an acceptor of data or commands.

T (Talker)-The ability of the Model 196 to send data over the bus to other devices is defined by the T function. Model 196 talker capabilities exist only after the instrument has been addressed to talk.

3-5

L (Listener)-‘he L function defines the ability of the Model

196 to receive device-dependent data over the bus. Listener

capabilities exist only after the instrument has been ad-

dressed to listen. SR (Service Request)--The SR function defies the ability

of the Model 196 to request services from the controller.

RL (Remote-Local)-The RL function defies the capabiligofe;vz Model 196 to be placed in the remote or local

PP (Parallel Poll)-I’he Model 196 does not have parallel polling capabilities.

DC (Device Clear)-The DC function defines the ability of the Model 196 to be cleared (iitialized).

DT (Device Trigger)-The ability for the Model 196 to have its readings triggered is defined by the DT function.

C (Controller)-The Model 196 does not have controller capabilities.

3.5 PRIMARY ADDRESS SELECTION

The Model 196 must receive a listen cornman dbeforeitwill respond to addressed co mmands over the bus. Similarly, the instrument must receive a talk

co mmand before it will transmit its data. These listen and talk commands are derived from the primary address of the instrument, which is set to 7 at the factory. Until you become more familiar with your instrument, it is recommended that you leave the address at this value because the programming I+ amples in this manual assume the instrument is p10grammed for that address.

The primary address can be programmed for any value between 0 and 30. However, each device on the bus must have a unique primary address-- a factor that should be kept in mind when setting the primary address of the Model 796. Most controllers also use a primary address; consult the controller instruction manual for details. Whatever address is used, it must be the same as the value specified as part of the controll& programming language.

TE (Extended Talker)-The Model 196 does not have extended talker capabilities.

LE (Extended Listener)-The Model 196 does not have SCtended listener capabilities.

E (Bus Driver Type)-The Model 196 has open-colle$or bus drivers.

Table 3-3. Model 196 Interface Function Codes

Interface Function Source Handshake cauabilitv

Acceptor Handshake capab&y Talker (Basic talker, Serial poll, Unaddressed to talk on LAG) Listener (Basic listener, Unaddressed to listen on TAG) Service Request capability Remote/Local capability No Parallel Poll capability Device Clear capability Device Trigger capability No Controller capability Open Collector Bus Drivers No Extended Talker capabilities No Extended Listener capabilities-

To check the presently programmed primary address, or to change to a new one, proceed as follows:

1. Press PRGM, 3,l. The current primary address will be

displayed. For example, if the current address is 7, the following message will be displayed:

07 IE

2. To modify the address, key in a new value (O-30) with

the numeric data buttons.

3. With the desired address value displayed, press the

ENTER button. The address will be programmed and the instrument wiU return to the previous operating state.

4. To store the address as the power up address, run Pro-

gram 30.

Note: For detailed information on using Programs 30 and 31, refer to paragraph 2.7.

3.6 CONTROLLER PROGRAMMING

A number of IEEE-188 controllers are available, each of which has its-own programming language. In th$ section, we will discuss the programming language for the HewlettPackard W-85.

3-6

IEEE-488 PROGFlAMMlNG

NOTE

amming information for using the IBM PC/XT

p=w

equipped with a Model 8573A IEEE-488 interface is contained in Appendix 8.

3.6.1 Controller Handler Software

Before a specific controller can be used over the IEEE-488

bus, it must have IEEE-488 handler software installed. With some controllers like the HP-85, the software is located in an optional I/O ROM, and no software installation is necessary on the part of the user. In other cases, software must be loaded tioom a diskette and initialized, as is the case with the Model 8573A interface.

Other small computers that can be used as IEEE-488 controllers may not support all IEEE488 functions. With some, interface pro* amming may depend on the particulsx interface being used. Many times, little “tricks” are necessary to obtain the desired results.

From the preceding discussion, the message is clear: make sure the proper software is being used with the interface. Often the user may incorrectly suspect that the hardware is causing a problem, when it was the software all along.

Some~of the statements have two forms, with the exact con-

figuration depending on the command to be sent over the

bus. For example, CLEAR 7 sends a DCL command over the bus, while CLEAR 707 sends the SDC command to a device with a primary address of 7.

Table 3-4. BASIC Statements Necessary to Send

Bus Commands

Action 1 HP-85 Statement

Transmits string to device 7. OUTPUT707; A$ Obtain string from device Z Send GTL to device Z Send SDC to device Z

ENTER707; A$ LUCAL 707 CLEAR 7’37

Send DCL to all devices. CLEhR 7 Send remote enable. Cancel remote enable.

REMOTE 7 LrJCAL 7

Serial poll device Z SPOLL<707> Send Local Lockout.

LOCAL LOCKUUT

Send GET to device. TRIGGER787 Send IFC. ABURTIO 7

3.7 FRONT PANEL ASPECTS OF IEEE-488 OPERATION

3.6.2 BASIC Interface Programming Statements

The progmmmin

clude examples written in HP-85 BASIC. This computer was

chosen for the examples because of its versatility in controlling the IEEE-488 bus. A partial list of statements for the HP-85 is shown in Table 3-4.

HP-85 statements have a one or three digit argument~that

must be specified as part of the statement. The first digit is the interface select code, which is set to 7 at the factory. The last two digits of those statements requiring a 3-digit argument specify the primary address. k the examples shown, the default Model 196 address (7) is shown. For a different address, you would of course change the corresponding digits in the programming statement.

g instructions covered @ this section in-

The following paragraphs discuss aspects of the front panel that are part of IEEE488 operation, including front panel error messages, IEEE-488 status indicators, and the LOCAL

key.

3.7.1 Front Panel Error Messages

The Model 196 has a number of front panel error messages The Model 196 has a number of front panel error messages associated with IEEE-488 programming. These messages associated with IEEE-488 programming. These messages are intended to inform you of certain conditions that may are intended to inform you of certain conditions that may occur when sendine device-deuendent commands to the occur when sendine device-deuendent commands to the instrument, as summarized in Table 3-5.

The following paragraphs discuss each of these messages in detail. Note that the instrument may be programmed to generate an SRQ (paragraph 3.9.X3), and the Ul error word can be checked for specific error conditions (paragraph 3.9.16) if any of these errors occur.

3-7

IEEE-488 PROGRAMMlNG

Table 3-5. Front Panel IEEE-488 Messages

NO REMOTE Instrument programkd Wifh REN

false. IDDC IDDCO

Uegal Device-dependent Command Illegal Device-dependent Command Option

TRIG ERROR Instrument triggered while it is still

urocessinc a urevious triczer.

SHORT TIME &xume~t c&-mot Store G&dings at

programmed interval. Readings will be stored as fast as the instrument can run.

BIG STRING Programmed display message ex-

ceeds 10 characters.

CAL LOCKED Calibration command sent with

calibration switch in the disable

CONFLICT

position. Data Store-Instrument cannot store readmgs at a high speed interval (1 to 14ms) while in an invalid state.

Storage will not occur. Calibration-Calibration com&tid is

ignored when instrument is~ in a+ invalid state (i.e. dB function).

NOTE: Error messages associated with translator software are located in paragraph 3.10.

No Remote Error

Note that the NO REMOTE Errol message is briefly displayed when the second statement above is executed.

IDDC ilIIega.I Device-Dependent Command) Error

An IDDC error ocCtis when the unit receives an invalid

command over the bus. For -pie, the command string

EIX includes an illegal command because the letter E is not

part of the inshwmenl% programming language. When an illegal command is received, the instrument will briefly display the following enor message:

IDDC

To correct the error condition, send only valid commands. Refer to paragraph 3.9 for device-dependent command pmgmmming details.

HP-85Rog?

amming Fxampl~To demonstrate an IDDC er-

ror, use the following statements:

REMOTE 707

OUTPIJT 707; * ‘ElXI ’

Note that the IDDC error message is briefly displayed when the second statement above is executed.

IDDCO (Illegal b&ice-Dependent Cmnman

d Option)

Error

A no remote error will occur if the instrument receives a device-dependent command and the REN (Remote Enable) line is false. In this instance, the following error message will be displayed on the front panel:

NO REMOTE

The error condition can be corrected by placing the REN line true before attempting to ~program the instrument.

HP-85 Programming Example--To demonstrate the NQ REMOT!Z error message, type in &e following lines:

LOCAL i

OUTPUT 707i L ( RiX’ ’

3-8

Sending the instrument a legal command with an illegal option that cannot be automatically scaled within bounds will result in the following front panel error message:

IDDCO

For example, the command WX has an iIlegal option (9) that is not paruf ~the instrument’s programming language. Thus, aleough~ the cq$rna$ (Y) itseg is valid, the option

(9) is not, and the IDDCO err01 will result.

To correct this error condition, use only valid command op-

lions, as discussed in paragraph 3.9.

HP-85 Pm

gmmming Example-Demonstrate an IDDCO er-

ror with the following statements:

IEEE-488 PROGRAMMlNG

REMOTE 707

OUTPUT 797; r r Y9X’ ’

Note that the IDDCO error message is briefly displayed when the second statement above is executed.

Trigger Ovemm Error

A trigger overrun error occurs when the instrument receives a trigger while still processing a reading from a previous

trigger. Note that orily the overrun triggers are ignored. These overrun triggers will not affect the instrument except to generate the message below. When a trigger overrun occurs, the foLIowing front panel message will be

displayed for approximately one second:

TRIG ERROR

HP-85 Pro

gramming Example-To demonstrate~~~a trigger overrun error, enter the following statements into the W-85 keyboard:

REMOTE 707

OUTPUT 707; 6 ‘ T3X’ ’

TRIGGERi07iZTRIGGER707

Cd Locked Error A cal locked error occurs when trying to calibrate the in-

strument over the bus with the front panel calibration switch in the disable position. Calibration commands will be ignored and the following message will be displayed briefly:

CAL LOCKED

Short Time Error

A short time error occurs when the instrument cannot store

readings in the data store at the programmed interval (Q tiriunand). However, the instrument will continue to store

readings as fast as its can run. The following message is

displayed briefly when a short time error occurs:

SHORT TIME

HP-85 Pm gramming Example--To demonstrate a short time

error, enter the following statements into the computer:

REMOTE 707

OUTPUT707;~rQ100F2T2X”

TRIGGER707

Note that the trigger overrun message is displayed after the END LINE key is pressed a third time.

Big String Error

A big string error occurs when trying to &splay a message

(using the ED command) that exceeds 10 characters. Blank display digits used in the message count~as characters. The

invalid message is ignored and the following message is displayed briefly when a big string error occurs:

BIG STRING

HP-85 Progr amming Example-Enter the following state: ments into the computer to demonstrate a big string qror:

REMOTE 707

OIUTPUT 707; r r DH0U@ARECYOU?X~ ’

When END LINE is pressed the second time the big string

error will occur because the message is made up oft I2

characters.

When END LINE is pressed the thiid time, the instrument wiU start storing readings in the buffer. However, since the instroment cannot make resistance measurements (FZ) at the selected interval (QlOO), short period errors will occur.

Conflict Error A conflict error occurs when trying to store readings at a

high speed interval (lms to 14ms) while the instrument is in an invalid state. After sending a command string that~ contains the interval command(Q), the following message is displayed briefly when a conflid error occurs:

CONFLICI

The entire command string will be ignored and the data store will not start.

Mid instrument states for high speed data storage are listed in Table 3-U

3-9

A conflict error also occurs when trying to send a calibration command over the bus while the instrument is in an invalid state, such as the dB function. The entire command string is ignored when a conflict error occurs.

HP-85 Programming Example-Enter the following statements into the computer to demons&ate a CONFLXT error:

REMOTE 707

OIJTPUT 707; r L QlWX s

When END LINE is pressed the second time, a conflict er-

ror will occur because data cannot be stored at the high speed interval of lms (Ql) with the instrument in the ohms function (F2). The entire command string will be ignored.

3.7.2 IEEE-488 Status indicators and LOCAL Key

The TLK, RMT, and LSN indicators show the present IEEE-488 status of the instrument. Each of these indicators is briefly described below.

TALK-The TLK indicator will be on when the instrument is in the talker active state. The unit is placed in thii state by addressing it to talk with the correct MTA (My Talk Address) command. TLK will be off when the unit is in the talker idle state. The instrument is placed in the talker idle state by sending it-an UNT (Untalk) ~command, addressing it to~listen, or with the IFC (Interface Clear) command.

REMOTE-The RMT indicator shows when the instrument is in the remote mode. Note that RMT does not necessarily indicate the state of the REN line, as the instrument must be addressed to listen with REN true before the RMT in-

dicator will turn on. When the instrument is in remote, all

front panel keys except for the LOCAL key will be locked

out. When RMT is turned off, the instrument is in the local mode.

LISTEN-The LSN indicator will be on when the Model 196 is in the listener active state, which is activated by addressing the instrument to listen with the correct MLA (My Listen Address) command. LSN will be off when the unit is in the listener idle state. The unit can be placed in the listener idle state by sending UNL (*ten), addressing it to talk, or by sending JFC (Interface Clear) over the bus.

LOCAJJYhe LOCAL key cancels the remote mode and restores local operation of the instrument;

STATUS INDICATORS

T‘K RHT LSN

El 0 Cl

LOCAL

HP-85 Statement

REMOTE 7 ABORT10 7 LOCALLOCKOUT LOCAL 707 CLEAR 7 CLEAR 707 TRIGGER707

Since all front panel keys except LOCAL are locked outs when the instrument is in remote, thii key provides a convenient method of restoring front panel operation. Press-

ing LOCAL will also hum off the RMT indicator and return

the display to the~normal mode if user messages were previously displayed with the D command.

Note that the LOCAL key will also be inoperative if the LLO

(Local Lockout) command is in effect.

Affect on Model 196

Goes into remote when next addressed. Goes into talker and listener idle states. Front panel controls locked out. Cancel remote. Returns to default conditions.’ Returns to default conditions. Trigsem reading in T2 and T3 modes.

3-10

3.8 GENERAL BUS COMMAND PROGRAMMING

General bus commands are those commands such as DCL that have the same general purpose regardless of the instrument. Cbmmands supported by the Model 196 are summarized in Table 3-6, which lists HP-85 statements necessary to send each command. Note that commands requiring a primary address assume that~ the Model 196 primary address is set to 7 (its factory default~addr&s).

3.8.1 REN (Rem’ote Enable)

REN is a uniline command that must be asserted by the controller to place the Model 196 in the remote mode. Simply setting REN true will not actually place the in&ument in remote; instead, the units must be addressed to

listen after REN is set true.

Generdly, remote enable should be asserted before attempting to program the instrument over the bus. Once the instrument is in r¬e, all front panel controls except

LOCAL will be inoperative. Normal front panel operation

can be restored by pressing the LOCAL key.

To place the Model 196 in the remote mode, the controller must perform the following sequence:

1. Set the REN line true.

2. Address the Model 196 to listen.

HP-35 Programming Example-Place the Model 196 in remote with the following statement:

Model 196 in the talker and listener idle states; The unit wilI respond to the IFC comman

d by cancelling front panel

TALK or LISTEN lights, if the instrument was previously

placed in one of those modes.

To send the IFC co nunand,

the controller need only set the

EC line true for a minimum of 100pec.

HP-85 Pmgrammi ng Example-Before demonstrating the LFC command, place the instrument in the talker active state with the following statements:

REMOTE 707

ENTER 707; A$

At this point, the RMT and TLK indicators should be on.

The lFC command can be sent by typing in the following statement:

FlEORTIU 7

Note that the TLK indicator hnns off when the Eb!D LINE key is presse-d.

3.8.3 LLO (Local Lockout)

The LLQ co nunand is used to lock out operation of the LOCAL key, thereby completely locking outs front panel operation of the instrument (recall that the remaining controls are locked out when the instrument is placed in remote).

REMOTE 787

When the END LINE key is pressed, the Model 196 should be in the remote mode as indicated by the RMT annunciator light. If not, check to see that proper bus connections are made, and that the instrument is programmed for the correct primary address (7).

Note that all front panel controls except~LOCAL (and, of course, POWER) are inoperative while the instrument is in remote. You can restore normal front panel operation by pressing the LOCAL button.

3.8.2 IFC (Interface Clear)

The IFC command is sent by the controller to place the

To send the LLO comniand, the controller must perform the following steps:

1. Set .4lN tie.

2. Place the LLQ command byte on the data bus.

To cancel local lockout and return control to the front panel,

REN must be set false by sending the LOCAL 7 command to the instrument.

HP-85 Progr amming Example-To verify LLO operation, enter the following statements:

REMOTE 707

LOCALLOCKOUT

3-11

After the second statement is executed, the LOCAL key will it does not set RBN false. be locked out.

HP-85 Programming Example-Place the instrument in the

To cancel LLO, type in the following statement:

remote modes with the following statement:

LOCAL 7

When END LINE is pressed, control to the front panel will be restored.

3.8.4 GTL (Go To Local)

The GTL command is used to take the instrument out of

the remote mode and restore operation of the front panel keys.

TO setid GTL, the controller must perform the following sequence:

1. Set KIN true.

2. Address the Model 196 to listen.

3. Place the GTL command byte on the data lines.

TheGTLco nunand wi!.l not cancel LLO (local lockout) since

REMott 707

Verify that the instrument is in remote.

Send GTL as follows:

LOCAL 7M7

Note that the instrument goes into the local mode, and that~

operation of the front panel keys has now been restored.

3.8.5 DCL (Device Clear)

The DCL co rmnand may be used to clear the Model 196 and return it to its default conditions. Note~that the DCL command is riot an addressed command, so ail instruments equipped to implement DCL will do so simultaneously. When the Model 196 receives a DCL c r&urn to either the factory default conditions listed in Tables 2-l and 3-7 or to the user saved default conditions.

ommand, it-will

Table 3-7. Factory Default Conditions

Mode 1 Command

I Multiplex Reading Function Data Format Selflrest EOI

SRQ

Internal Digital Filter Filter Data Store Interval Data Store Size

R=w Rate

Al BO

Kil

MO Nl

status

Enabled A/D converter DC volts

Send prefix with reading Clear Enable EOI and bus hold-off on X Disabled Enabled Disabled One-shot~into buffer One reading

3ocN

6%d, line cycle integration Continuous on external trigger No delay CR LF l&a&d

3-12

IEEE-488 PROGRAMMING

To send the DCL command, the controller must perform the following steps:

1. Set ATN true.

2. Place the DCL conuixmd byte on the data bus.

Notes:

1. DCL will return the instrument to the default line frequency setting.

2. DCL will not have any affect on the -nt IEEE address:

HP-85 Programming Example-Place the unit in an operat-

ing mode that is not a default xondition. Now enter the

following statement into the I-Jl’-85 keyboard:

CLEAR 7

When the END LJN!? key is pressed, the inslnnnent w to the default conditions.

3.8.6 SDC (Selective Device Clear)

The SDC command is an addressed command that performs essentially the same function as the DCL command. However, since each device must be individuslly addressed, the SDC command provides a method to clear only a single, selected instrument instead of clearing all instruments simultaneous1 as is the case with DCL. When the Model 196 receives t to either the factory default conditions listed in Tables 3-7 and 2-1 or to the user saved default conditions.

e SDC command, it will return

When the above statement is executed, the instrument retums to the default configuration.

3.8.7 GET (Group Execute Trigger)

GET may be used to initiate a Model 196 measurement sequence if the instrument is placed in the appropriate trigger mode (see paragraph 3.9). Once triggered, the i&ument~~will perform the measurement sequence in accordance with previously selected rate and sample parameters.

To send GET, the controller must perform the following sequence:

1. set !irN low.

2. Address the Model 196 to listen.

3. Place the GET command byte on the data bus.

HP-85 Programming Example--Type in the following statements to place the instrument in the correct trigger mode for purposes of this demonstration:

REMOTE~707

OCITFILIT 707; L * T3X’ ’

Now trigger the measurement sequence by sending GET with the following statement:

TRIGGER707

When the END LINE key is pressed, the measurement sequence will be triggered.

To transmit the SDC command, the controller must perform the following steps:

1. Set ATN true.

2. Address the Model 196 to listen.

3. Place the SDC command byte-on the data bus.

Notes:

1. SDC will return the instrument to the default line frequency setting.

2. SDC will not have any affect on the current IEEE address.

HP-85 Programming Example-Using several front~panel

controls, alter instrument states from the default wnfiguration. Send SDC with ~the following statement:

CLEQR 707

3.8.8 Serial Polling (SPE,SPD)

The serial polling sequence is used to obtain the Model 196 serial poll byte. The serial poll byte contains important information about internal functions, as desoibed in paragraph 3.9.13. The serial polling sequence can also be used by the controller to determine which instxument on the bus has asserted SRQ (Service Request).

F~,rial polling sequence is generally conducted as

1. The controller sets KiW true.

2. The controller then places the Sl’E (Serial Poll Enable) command byte on the data bus. At this paint;~~all active devices are in the serial poll enabled mode and waiting to be addressed.

3-13

IEEE-488 PROGRAMMING

3. The Model 196 is then addressed to talk.

4. The controller sets Al-N false.

5. The instrument places its serial poll byte on the data bus to be read by the controller.

6. The controller then sets ATN true and places the SPD (Serial Poll Disable) command byte on the data bus to end the serial polling sequence.

Once instruments are in the serial poll mode, steps 3 through 5 above can be repeated by sending the correct talk

address for each instrument.

HP-85 Programming Example-The HP-85 SPOLL statement automatically performs the sequence justmdescn%ed. TO demonstrate serial polling, type in the following

statements:

AEllOTE 707

S= SPOIL (797)

DISP s

When the above statements are executed, the Model 196 is serial polled, and the decimal value of the serial poll byte is displayed on the computer CRT.

Commands that affect instrument operation will trigger a

reading when the command is executed. These-bus com-

mands affect the Model 196 much like the front panel con-

trols. Note that commands are not necessarily executed in

the order received; instead, they will be executed in

alphabetical order. Thus to force a particular command se-

quence, you would follow each command with the execute

character(X), as in the example string, Upcnx, which will reset the instrument to factory default conditions and then select the ohms function.

Device-dependent comman ds can be sent either one at a time, or in groups of sweral commands within a single

string. Some examples of valid command strings include: FOX-Single command string.

FOKlPOROX-Multiple command string. T6 X-Spaces &e ignored.

Typical invalid command strings include: ElX-Invalid command, as E is ndt one of the instrument

commands.

=X-Invalid co nunand option because 15 is not an option

of the F command.

3.9 DEVICE-DEPENDENT COMMAND PROGRAMMING

IEEE-488 device-dependent commands are used with the Model 196 to control various operating modes such as function, range, trigger mode and data format. Each command is made up of a single ASCII letter followed by a number representing an option of that command. For example, a command to control the measuring function is programmed by sending an ASCII “F” followed by a number representing the function option. The IEEE-488 bus actuall these commands as data in that ATN is false when ;I mands are transmitted.

A number of commands may be grouped together in one s&in . AS cl3

A command strin is usually terminated with an

“Y character, whx 3-l tells the instrument to execute

the command string. Cornman ds sent without the execute character will not be executed at that time, but they will be retained within an internal command buffer for execution at the time the X character is received. If any errors occur, the instnunent will displa a error messages and generates an

propriate front panel

If programmed todo

so.

treats

e com-

If an illegal COmIMn d @DC), illegal command option

(IDDCO), is sent, or if a command string is sent with REN

false, the string will be ignored.

Device-dependent commands that control the Model 196

are listed in lkble 3-8. These commands are covered in detail in the following paragraphs. The associated programming

scamples show how to send the commands with the HP-%

NOTE

Programming examples assume that the Model 196 is at its factory default- value of 7.

In order to send a device-dependent-command, the controller must perform the following steps:

1. Set MN true.

2. Address the Model 196 to listen.

3. set MN false.

4. Send the command string over the bus one byte at a

time.

3-14

Table 3-8. Device-Dependent Command Summery

Auto Auto Auto Auto

3wmv390mv300&4m+4 3ol n hto 300 n

3v3v3mA3mA 3M

3ov3GmY3onA3GmA 3okn

IEEE-488 PROGRAMMING

hfger Mode

-I3 T4

T.5

3’hd 3’/ld 3’hd 3Md 3%d(Rl-4) 5’hd 5’hd

4Hd 4’hd 4%d 4Md 4%d@l-R4) 5Md 5’hd 5’hd

5Vtd 5’hd 5Hd 5Hd

6Hd 5’hd 5’hd 5Md 6Hd(Rl-R6) 5Md 5Yzd 6’hd

5w=-Rn

5’/zd@S-I(7

5’hd

5Md(R7j

5’hd 5%d 5Yzd

Integration period: 3Yzd=3l&sec, 4%d=ZS9nwec, 3%d and 6%d=Liie cycle

Cmtinuous on Talk One-shot on Talk Continuous on GET One-shot on GET Continuous on X One-shot on X Continuous on External Trigger One-shot on External Trigger

5’hd

3.9.7

3-15

IEEE-488 PROGRAMM,ING

Table 3-8. Device-Dependent Command Summary (Cont.)

Mode Command

Reading Mode BO

Data Store Size

Data Store Interval

QO Qn

Value

Vjnn.nnnn 01

V+n.nnmqnE+

Calibration

Default Conditions

Lo Ll

Data Format

:; G2

SRQ

MO Ml

M32

EOI and Bus Hold-of;

E E

Terminator

m Yl

Y2 n

SthLS

u3 U4 u5 U6

Multiplex

A0 Al

Description Readings from A/D converter Readings from A/D converter

Readings from data store Readings from data store Continuous data store mode Continuous data store mode

Data store of no (n=l to 500) One-shot into buffer

n=intend in milliseconds (lmsec to 999999msec) Calibration value, zero value

Calibrate first point using value (V) Calibrate second point using value (V)~

Restore factory default conditions and save (Ll)

Save present machine states as default conditions

Readings with prefixes. Reading without~ prefixes. Buffer readitlgs with prefixes and buff& locations. Buffer readings without prefues and with buffer locations. Buffer readings with prefixes and without buffer locations. Buffer read&s without orefues and without buffer

locations. “~~

Disable Reading overflow Data store full Data store half full Reading done Ready Error

Enable EOI and bus hold-off on X Disable EOI, enable bus hold-off on X Enable EOI,, disable bus hold-off on X Disable both EOI and bus hold-off on X

CR LF 4F_CR~

CK LF

Send machine status word Send error conditions Send translator word Send buffer size Send average reading in buffer Send lowest reading in buffer Send highest reading in buffer Send current value Send input switch status (front/rear)

Auto/Cal multiplex disabled Auto/Cal multiplex enabled

Parag

3.9.8 3.9.8

3.9.9 3.9.9

3.9.9

3.9.10

s9.11

3.9.12

3.9.13

3.9.14

3.9.15

3.9.16

3.9.17

3-16

Table 3-8. Device-Dependent Command Summary (Cont.)

IEEE-488 PROGRAMMING

Mode Delay self-test Hit Button Display

Exponential Filter

Command Desqiption

n=delay period in milliseconds, (Omsec to 6OOOOqsec)

JO Te&ROM, RAM, E’PROM

I-h

Hit front panel button munber n Display up to 10 character message. a=character 3.9.21

Cq@ display mode Internal filter off

Internal filter on

NOTE

REN must be true when sending device-dep~+nt commands to the instrument, or it will ignore the command and display a bus error message.

General HP-85 Pmgramming Example-Device-dependent commands may be sent from the HP-85 with the following statement:

OUTf’UT707;AB

A!$ in this case contains the ASCII characters representing the command string.

Paragraph

3.9.18

3.9.19

3.920

3.9.22

; ,.

X character will be transmitted to the instrument. No mode changes will OCCUI withH~$ example because no other com-

man& were sent. Note that the instrument remains in the listener active state after the command is transmitted.

3.9.2 Function (F)

The function command allows the user to select the type

of measurement made by the Model 196. When the instrument responds to a function command, it will be ready to take a reading once the front-end is set u may be programmed by sending one o

The function

the following

commsrlds:

3.9.1 Execute (X)

The execute command is implemented by sending an ASCn

“X” over the bus. Its purpose is to direct the Model 196 to execute other device-dependent commands such as F (function) or R (range). Usually, the execute character is the last byte in the comrn+nd.string (a r+mber of commands may k FTC! together mto one strmg); bowever, there may

amumstmces where it is desrable to send a command string at one time, and then send the execute character later on. Command strings sent without the execute character will be stored within an internal command buffer for later execution. When the X character is finally transmitted, the stored comman

ds will be executed, assmn-

ing that alI commands in the previous string were valid.

HP-85 Pmgramming E%%nple-Enter the following statements into the HZ-85 keyboard:

REMOTE 707

UUTPUT~707;“X”

When the END LINE key is pressed the second time, the

FO = DC Volts Fl = AC Volts FZ=Ohms F3 = DC Current F4 = AC Client F5 = ACV dB

F6 = AC4 dB

F7 = Offset Compensated Ohms

Upon power up, or after the instrument receives a DCL or

SDC command, the Model 196 will return to the default

condition.

HP-85 Programming Example-Place the instrument in the ohms function by pressing the OHMS button and enter the following statements into the HP-85 keybq%d:

REMOTE 707

OUTPUT707i”F0X”

When END LINZ is pressed the second time, the instrument changes to DC volts.

3-17

\EEE-488 PROGRAMMING

3.9.3 Range (R)

The range command gives the user control over the sensitivity of the instrument. This command, and its options,

erform essentialI the same functions as the front

kge buttons. &nge commands parameters an$ the respective ranges for each measurings functjon are~sum_ marized in Table 3-9. The instrument wiil be ready to take a reading after the range is set up when responding to a

range command.

Upon power up, or after the instrument receives a DCL or

SDC co mmand, the Model 196 will return to the default

condition.

HP-35 Programming Example-Make sure the instrument is in the autorange mode and then enter the following

,statements into the HP-85:

REMOTE 707

OUTPUT 707; ’ ‘R3X’ 9

When the END LINE key is pressed the second time, the instrument cancels the autorange mode, and enters the R3 range instead.

anel

ZO = Zero disabled.

Zl = Zero enabled.

22 F Zero enabled using a zero value (V).

Sending Zl has the same effect as pressing the ZERO but-

ton. Zero will enable, and the display will zero with the

mput signal becoming the zero baseline level. The baseline wih be stored in Program ZERO.

The 22 command is used when a zero value, using the V

command, has already been established. When the 22 command is sent, subsequent readings represent the difference

between the input signal and the value of V. Also, the value

of V is stored in Program ZERO. For example, with 0.5V on the in ut,

result WI Ii

-1.5v (0.5 -2.0 = -1.5).

Sending the 22 comman

is the same as sending the Zl command. See paragraph

3.9.10 for more information on using the V command.

Upon power up or after the instrument receives a DCL or

SDC command, the Model 196 %ill return to the default

condition. The value of V will reset to zero.

sending the command strings V2XZ2X will

zero being enabled and the instrument reading

d without a V value established

3.9.4 Zero (if)

Over the bus, the zero modifier can be controlled in the same way that it is controlled from the front panel. Refer to paragraphs 2.6.2 and 2.7.15 Qro

description of the zero modifier. TE trolled by sending one of the folkowing zero comman

. . .

the bUS:

Command DCV ACV DCA ACA

Ro Auto Auto Auto Auto

Rl 3oomv 3oOnN 300 /LA 300 @A E 3i :: 3: :: 322 3;s

R4 300 v 300 v 3oomA 3oomA

rogram) for a complete

e zero modifier is con-

dsover

Table 3-9. Range Command Summary

300 0 Auto Auto 300 0

300 kbl AU&J Auto 30 kQ

HP-85 Programming Example-Set the instruments to the 3V DC range. With the front panel ZERO button disable

e zero mode, if enabled, and enter the following

stat

ements into the HP-85 kevbosrd:

REMOTE 707 OUTPUT707;‘1111Xy’ OUTPUT 707; ’ ‘ZZX’ 3

Range

Offset Compensated

Ohms

Auto Auto

30 3kil m Auto Auto Auto Auto 30 3kS kD

ACV dB ACA dB Ohms

Auto Auto

3-18

IEEE-488 PROGRAMMING

After the END LINE key is pressed the third time, the ZERO indicator will turn on with a zero baseline level of 1V DC. The zero value will also be stored in Pmgram ZERO.

3.9.5 Filter (P)

The filter command controls the amount of filtering applied to the input signal. The Model 196 filters the signal by

taking the weighted average of a number of suicessive reading samples. Since noise is mostly random in nature, it can be largely cancelled out with this method.~The number of readings averaged (filter value) can be from 1

to 99. The filter value can be programmed by sending one of the following commands:

PO = Filter disabled. Pn = Filter on with a value of n. Where n can be from 1

to 99.

Upon power up or after the instrument receives a DCL or

SDC command, the Model I96 will return to the default condition.

Notes:

1. A filter value sent over the bus is stored in Program FIUER, replacing the previous filter value.

2. Keep in mind that each function can have its own

unique filter value.

When the END LINE key is pressed the second-&ne,,the falter will turn on and have a filter value of 20.

3.9.6 Rate (S)

The rate command controls the integration period and the usable resolution of the Model 196. lhble 3-10 lists the usable resolution on each function for the four S modes. The integration period is dependent-on usable resolution as follows:

3Yzd resolution = 3l8psec 4Md resolution = 259msec 5Yzd resolution = Line cycle*

6Yzd resolution = Lime cycle* “20msec for 5OH2, l6.6msec for 6OHz.

Upon power up or after the instrument receives a DCL or SDC command, the Model 196 will return to the default

condition.

HP-85 Programming Example-From the front panel, Seth the display of the Model 1% for DCV at 6Yzd resolution. Now enter the following statements into the HP-85

REMOTE 707

OUTPUT707;“S1X3’

Ew85Rogr

amming BxamphGWnh the front panel FKFER

indicator off, enter the following statements into the HF-85:

REMOTE 707

OlJTPUT707;“PZOX”

Table 3-10. Rate Command Summary

Command

so Sl

DCV

3Yzd 4Yzd 5Yzd

6%d

ACV

3%d

4Yzd 5%d

5%d

DC4

3Yzd 4Yzd 5Yzd

5Yzd

ACA

3Yzd 4Yzd 5Yzd

5r/zd

[

Integt

m peril

Id:

bd=259msec, 5Y’a ana bYza=Lme cycle.

When END LINE is pressed the second time, the Sl rate will be selected.

LCV dB

5Yzd

5Yzd 5Yzd 5Yzd 5Yzd

5Yzd

AC4 dB

5%d

5Yzd 5Yzd 5Yzd 6Yzd

,.v. .

,~~

3.19

IEEE-488 PROGRAMMING

3.9.7 Trigger Mode (T)

Triggering provides a stimulus to begin a reading conversion within the instrument. Triggering may be done in two basic ways: in a continuous mode, a single trigger command is used to start a continuous series of readings; in a one-shot trigger mode, a separate trigger stimulus is required to start each conversion. The Model 196 @eight trigger commands as follows:

TO = Continuous on Talk

Tl~ = One-shot on Talk

T2 ~= Continuous on GET I3 = One-shot on GET T4 = Continuous on X T5 = One-shot on X T6 = Continuous on External Trigger T7 = One-shot on External Trigger ~ ~~~~~

The trigger modes are paired according to the type of stimulus that is used to trigger the instrument. In the ‘IO

and~Tl niddes, t+iggering is performed by addressing the Model 196 to talk. In the T2 arid T3 modes, the IEEE-488 multiline GET command performs the trigger function. The instrument execute (X) character provides the triggeT

stimulus in the T4 and T5 modes. External trigger pulses

provide the trigger $imuhrs in the T6 ,and T7 modes.

Upon power up or after the instmment receives a DCL or

SDC cbmmtid, the Model 196 will return to the default

condition.

NOTE

With the instrument in the T6 and T7 trigger

modes, the front panel ENTER button can be used to trigger readings. See paragraph 2.8 fqor details.

In this example, the ENTER statement addresses the Model 196 to talk, ate which point a single reading is triggered. When the reading has been processed, it is sent out over to the bus to the computer, which then displays the result.

3.9.8 Reading Mode (B)

The reading mode command parameters allow the selection of the source of data that is transmitted over the IEEE-488 bus. Through this comman of data from the A/Dmv%ter (normal DMM readings) or the buffer (data store).~The reading mode commands are as follows:

BO = A/D converter readings Bl = Data Store readings

Upon power up or after the instrument receives a DCL or SDC command, the Model 196 wiIl return to the default condition.

When in BO, normal A/D reading+ will be sent~. In a continuous trigger mode, readings will be updated ate the conversion rate. The Bl command is used to access readings from the buffer. When the Bl command is sent, subsequent readings will be taken from consecutive buffer locations beginning with the first memory location (001). Once all readings have been requested, the unit will cycle back and begin again.

HP-85 Programming Example-Enter the following

statements into the computer to send a reading over the

bus and display it on the computer CRT.

REMOTE 707

OUTPUT 707~; ’ ’ EnXI ’

ENTER 707 i A$

DISP A9

d, the user has a choice

HP-85 Pmgmmming Exampl+Place the instrument in the

one-shot on talk mode with the following statements:

REMOTE 707

OLlTPUT707j~“Tl:x:”

One reading can now be triggered and the resulting da@ obtained with the following statements:

ENTER 787; A4:

DISP A$

3-20

The second statement above sets the instrument to the AID

converter reading mode. The third and fourth statements acquire the reading and display it~~on the CRT.

3.9.9 Data Store Interval (Q) and Size (I)

The data store is controlled by the interval command (Q). and the size command (I).

IEEE-488 PROGRAMMING

J.nterval

With the Q

comman d, the user can select the interval that the instrument will store readings or select the one-shot mode. In one-shot, one reading will be stored each time the instrument is triggered. The Q cmnman

d is in the

following form: QO=Oneshot into buffer.

Qn=Set storage interval in millisec (lmsec to 999999tiec).

To use the data store in the one-shot mode (QO), the instrument must be in a one-shot trigger mode (cc n, T5 or T7). In the QOTl mode, one reading will be stored each lime the instrument is addressed to talk. In the QClI3 mode, each GET co mmand will cause one reading &q be store& ln the QOT5 mode, each instrument execute character (X) will cause a reading to be stored. Fmally, in the Qm mode, each external trigger pulse will cause a r&ling to be stored. If the instrument is in a continuous trigger mode (To, T2,

T4 or T6), any IDDC error will occur.

NOTE

With the instrument in the T7 trigger mode, the front uanel ENTER button can be used to manuallv store’readings into the buffer. Each press of thk ENTER button wilI store one reading in t&e buffer.

See paragraph 2.8 for details.

To store readings at a selected interval (Qn), the instrument must be in a continuous trigger mode f,lU, T2, X, T6). &en the selected trigger occurs, the storage process will commence.

NOTE

With the instrument in the T6 trigger mode, the front panel ENTER button can be used to start a

series of readings to be stored in the buffer. The

storage interval and buffer size are determined by the Qn and I co mmands respectively. See paragraph 2.8 fork details.

siie

IO=Continuous storage mode. In=Set data store size to n (1 to 500).

In the continuous data storage mode (IO), storage will not stop after the buffer is filled (500 readings), but will proceed back to~the first memory location and start oven&kg data. V+h the Innn command, the storage process will stop when the defined number of readings have been stored. In this case the buffer is cdnsidered to be fuli.’

Notes:

1. When the Q or I co

mmand is sent, ‘c---i’ will be

displayed until the first trigger occurs.

2. The data store can be disabled by sendine: the F command. Storage will again resume’when &appropriate trigger occurs.

The instrument must be in a valid operating state (see %ble 3-11) in order to use the high speed data store capabilities. The high speed intervals are lmsec through

lknsec. The instrument display will blank while the instrument is storing readings at high speed. If the ins&ument~ is not in a valid operating state for high speed storage, a conflict error will be displayed briefly and storage will not occur.

The short time error message indicates that the in&umentcannot store readings at the programmed interval

rate. Instead, readings will be stored as fast as the in-

strument can run.

With S2 or 53 asserted, the fastest valid storage interval

(I) is 3lmsec and 35msec respectively. A shorter inter-

val will result in a short time error when the storage pmc&s is started. Readings will be stored as fast as the instrument can run.

Either during or after the storage process, readings may be recalled by using the Bl command as described in the previous paragraph. Also, the highest, lowest and average reading in a full buffer can be recalled by sending the ,appropriate U commands. See paragraph 3.9.16 for information on using the U commands.~

Upon power up or after the instrument receives a DCL of SDC command, the Model 196 will return to the defaults condition.

The size of the data store can be controlled by one of the

following I commands.

~Hp-85 Programming Example-Enter the program below

to enable data store operation and obtain and display 100 readings on the computer CRT:

3-21

PROGRAM

COMMENT3 _.__.. _-_-. .~

10DItlA8C25l

20 REMOTE 70.7 Send remote enable. 30 OUTPUT 707; Set trigger mode, and

‘1T2~3001100X” storage parameters.

40TRIGGER707 Start storage process. 50 OUTPUT 707: Set read mode to data

s ‘BiGBX”

StOK?.

60FORI=lTO100 Set counter for 100

loops.

70ENTER707iR8 Get a reading.

00 DISPA$ Display reading. 30 NEXT I toop back for next

reading.

100 END

After entering the program, press the HP-85 RUN key. The program will set the store size to IOO (line 30), enable the

data store (line 4O), turn on the data store output (line 50), and then request and display all 100 readings (lines 6O-l.OO).

,.$ @is example, note that only as many significant digits

as necessary need be sent. In this case, the exact value is assumed to be 3OMxxx) even though only the first two digits were adually sent.

Digital Calibration-When performing digital c&ration, two points must be caliiated on each range. The first

caliiation value should be approtiately full range and the second calibration value should be approximately zero. After the second calibration value is sent over the bus, permanent storage of the two values will occur.

In order to send calibration values over the btxs, the caliia-

tion command (C) must be sent after the value command

(V) is sent. The calibration command takes on the followmg form:

cO=Calibrate first point using value (V) Cl=Calibrate second point using value Iv)

The following example first sends a caliiration value of 3

and then a calibration of 0.

3.9.10 Value (V) and Calibration (C)

Otie ;Idvanced feature of the Model 196 is its digital c&bration capabilities. Instead of the more difficult method of adjusting a number of potentiometers, the user need only apply an appropriate calibration signal and send the caliiration value over the bus.

The V command is also used to program a zero value (see paragraph 3.9.4).

Fhy command may take on either of the following

VM.mlNm Vn.nnnnnnE+n

Thus, the following two WI V3.OE+l

comman

ds would be equivalent:

Table 3-11. High Speed Data store

Data Store Valid Reading

Interval

Rate

WXCOX VOXCIX

If the calibration value is greater than 3030000 counts (at 61Ad resolution) an lDDC0 error message will be displayed on the Model 196.

CAUTION

Precision calibration signals must be connected to the instrument before attempting calibration, otherwise instrument accuracy will be affected. See Section 6 for complete details on calibrating the instrument either from the front panel or over

the bus.

. . .~.

Valid

Valid Valid Date

FundiOnS Ranges* Store Site*

3-22

QL Q2

Q3-Q14 so, Sl

FO, FYL F3, F4 Rl-R7 Il-I500

FO, F-l, F3, M Rl-R7

Il-I500

*Data store size IO (continuous) and Ro (autorange) cannot be used in

the high speed data store mode.

IEEE-488 PROGRAMMING

3.9.11 Default Conditions (L)

The LO cotiand allows the user to return the instrument

to the factory default conditions. Factory default conditions

are set at the factory and are listed in Tables 3-7 and 2-l. The imtmment wiIl power up to these default conditions. The current IEEE address and line frequency setting of the

instrument are not affected by the M command.

The Ll command is used to save the current instrument

conditiO116. The ir!StrUment wiu then power up t0 these

default conditions.

Any of the options of the following device-dependent com-

mar& can be saved as the default conditions:

A (multiplex), F (function), N (internal filter), P (digital filter), Q ad 1 (data Store h-ttemd and Sue), R (ra%d, s

(rate), W (delay), and Z (zero).

The L command options are as follows:

L&Restore instrument to factory default conditions and

save (Ll).

Ll=Save present machine states as the default conditions.

Notes:

1. Sending Ll is equivalent to running program SAVE.

Thus, the current IEEE address and line frequency set-

ting are saved by IJ.

2. Sending Ill is equivalent to running Program 37 (Reset) and then Program 30 (Save), thus:

A. User saved defaults will be lost since fact&y default

conditions will be saved.

B. M will not change the current IEEE address and line

frequency setting, and will save them as the default conditions.

~&&j fiogmmming E-@-&t the Model 196 to the ohms function, and enable zero and filter. Now, enter the

following statements into the computer:

REMOTE 787

CIUTPIJT~~~;“L~X”

After pressing END LINE the second time, cycle power on the Model 196 and note that the hmment retins to the

conditions initially set in this example.

3.9.12 Data Format (G)

The G comman instrument sends over the bus. Readings may be sent with or without prefixes. Prefixes are the mnemonics preceding the reading and the buffer memory location. Figure 3-6 further clarifies the general data format. The G comniands are as follows:

d controls the format of the data that the

+NONE’NO READINGS IN

DATA STORE

DCV=OC VOLTS ACV=AC VOLTS OHH=OHMS OCO=OFFSET COMPENSATED OHNS DCI=DC AMPS ACI=AC ANPS dBV=AC dB VOLTS dBI=AC dB AMPS

pREFIx~~A~~“~A ‘: D’G”s~~~~~R,,~O~~~~~~N

NDCV +I.234567 E + 1 .ESOO CR LF

1 L7”;;;;g!yR

EXPONENT

Figure 3-6. General Data Format

3-23

IEEE-408 PROGRAMMlNG

GO = Send single reading with prefixes. Examples:

NDCV-1.234567E+D (A/D reading) NDCV-1234567E+O,BOOl (buffer reading)

Gl = Send single reading without pwfixes. Etim$es:

-1234567E+O (A/D reading)

-1234567E+0,001 (buffer reading)

G2 = Send alI buffer readings, separated by co-s, with

prefixes and buffer memory locations. Examples:

NDCV-l.Z34567E+O,BOOl,NDCV-1.765432E+ O,BOO2, etc.. .

G3 = Send aII buffer readings, separated by commas,

without prefixes and with buffer memory locations. Example: -1.2X!WE+O,IX?~-1.765432E+O,M?2, etc...

G4 = Send alI buffer readings, separated by commas, with

reading prefixes and without~ memory buff&r locations. Example: NDCV-1.234567E+O,NDCV-1.765432E+O,etc...

G5 = Send all buffer readings, separated by co-s,

without reading prefixes and without buffer memory locations. Example:

-1234567E+O,-1.765+0, etc...

Upon power up or after the instrument receives a DCL or

SDC ~command, the Model 196 will return to the default

CO*diti0*.

Notes:

HP-85 Progr

amming Example-To place the instrument in the Gl mode and @@n a reading, enter the following statements into the m-85 keyboard:

REMOTE787

When the second statement is exerted, the instrument wilI than

e to the Gl mode. The last two statements acquire

data fr

om the instiment and display the reading string

on the CRT. Note that no prefii or suffix appears on the

da@ string.

3.9.13 SRQ Mask (M) and Serial Poll Byte Format

The SRQ command controls which of a number of conditions within the Model 196 wiU cause the instrument to request service from the controller by asserting an SRQ. Once an SRQ is generated, that serial p* byte can be checked to

determine if the Model 1% was the instrument that asserted the SRQ and if so, what conditions can be checked by using the Ul command, as described in paragraph 3.9.33.

1. The B command affects the source of the data. In the BO mode, the bus data wiIl come from the A/D converter. In the Bl mode, the data wiIl come from the buff&

2. The Bl command must be asserted when using the G2 through G5 modes.

3. Pro~ammed terminator and EOI sequences appear at the&d of each reading in the GO and Gl mddes, but are transmitted only at the end of the buffer in the G2

through G5 modes. No terminator is sent if in G2 through G5 modes while in BO (data from A/D). ~‘~ ~~~

BIT

POSITION

VALUE

DECIMAL

WEIGHTING

I=SRQ BY 196 (STATUS BYTE ONLY) I=READING OVERFLOW

I=ERRDR I= BUFFER FULL I-READY

The Model 196 can be programmed to generate an SRQ

under one or more of the following cqncjitions:

1. When a reading is completed or an overrange condition oaxrs.

2. If a bus error occurs.

3.~ When the data store is full.

4, men the data store is yz full.

5. If a trigger overrun error occurs.

6;~When the bus is ready.

l=BUFFER HALF FULL I’READING DONE

3-24

Figure 3-7. SRQ Mask and Serial Poll Byte Format

IEEE-488 PROGRAMMING

Upon power up or after a DCL or SDC co~%id is received, SRQ is disabled.

SRQ Mask--The Model 196 uses an internal mask to determine which conditions will cause an SRQ to be generated.

Figure 3-7 shows the general format of this mask.

SRQ can be programmed by sending the ASCII letter “M” followed by a decimal number tom set the appropriate bit in the SRQ mask. Decimal values for the various bits are summarized in Table 3-12. Note that the instrument may be programmed for more than one set of conditions simultaneously. To do so, simply add up the decimal bit values for the required SRQ conditions. For example, to enable SRQ under reading overflow and buffer full conditions, send M3X. To disable SRQ, send MOX. This command wi!.l clear all bits in the SRQ mask.

Table 3-12. SRQ Command Parameters

Command ( Cond#qn to Generate SRQ

MO Ml

Disable Reading overflow Data store full

iii

Data store half full Reading done

ibE3

M32

Ready Error

.-~~

Bit 5 (Error)-Set when one of the following errors have occurred:

1. Trigger Error

2. Short Tie

3. Big String

4. UncaGxated

5. Cal Locked

6. Conflict

7. No Remote

8. IDDC

9. IDDCO

.~~

10. Translator _

The nature of the error can be determined with the Ul com-

mand asexplained in paragmph 3.9.16. An explanation of each error can also be found in paragraph 3.9.X

Bit 6 [SRQ)-Provides a means to determine if an SRQ Was asserted by the Model 196. Jf this bit is set, service was re-

quested by the instrument.

Bit-7-Not used and always set to zero.

Note that the status byte should be read to clear the SRQ line once the instroment~has generated an SRQ. All bits

in the status kyte will be latched when the SRQ is generated. Bit 6 (RQS) will be cleared when the status byte is read.

Serial Poll Byte Format-The serial poll byte contains in-

formation relating to data and error conditions with@ the

instrument. The general format of the serial poll byte (which is obtained by using the serial polling sequence, as described in paragraph 3.88) is shown k Figure 3-7.

The bits in the serial poll byte have the following meanings: Bit 0 (Reading Overtlow)-Set when an overrange input is

applied to the inshument. Bit 1 (Buffer Full)-Set when the defied buffer size is full. Bit 2 (Buffer Yz Full)-Set when half the defined buffer size

isfoll.

Bit~3 (l%adirg Done)-Set when the instrument has completed the present reading conversion.

Bit 4 (Ready)-Set when the instrument has processed all

previously received commands and is ready to accept ad-

ditional commands over the bus.

I-IF-85 Programming Example-Enter the following program into the m-85:

PROGRAM

10 REMUTE 797 @ CLEAR 7

COMMENTS

Set up for remote

operation, clear instrument;~~~

20 UIJTPUT 707; r r M32X’ y Promm for SRQ on

Ipwo.

30 OIJTPLIT 7M7; 8 ‘KSX’ ’

40 S=SFOLL<707:) ~~IF~OTEIT(SIS)THEN~~ WaitforSRQemor.

50 DISF “B7 B6 B5 E4 B3 BZ Identify the bits.

El RQ”

60 FOR I=7 TOM STEF~-1 ~BDISFEIT<SII).:

80 NEXT I 90 I!ISF

l&3 END

Attempt to program ille@bptioti. -

Serml poll the

insbxment.

Loop eight times. Displav each bit

po&i&.

3-25

Once the program is entered and checked for errors, press the HP-85 RUN key. The computer first places the instru-

ment in remote (line lo) and then programs the SRQ mode of the instrument (line 20). Line 30 then attempts to program an illegal command option, at which point the instrument generates an SRQ and sets the bus error bit in its status byte. The computer then serial polls the instrument (line 4O), and then displays the status byte bits in proper order on the CRT. In this example, the SRQ (B6) and error (85) bits are set because of the attempt to program an illegal command option (K5). Other bits may also be set

depending on instrument status.

3.9.14 EOI and Bus Hold-off Modes (K)

mode is that no bus commands will be missed whilethe instrument is processing commands previously received.

The hold off period depends on the commands beingprocessed. Table 343 lists hold off times for a number of different commands. Since a NRFD hold off is employed, the handshake sequence for the X character is complete.

NOiE

With KD or Kl asserted, hold-off will also occur on

an EOI and a terminator. These delays allow for

proper operation of the Translator software, since

“X” cannot be used in Translator words.

The K command allows control over whether or not the in-

strument~sends the EOI command at the end of its data

HP-85 Programming Example-To program the instrument for the K2

&in and whether or not bus activity is held off (through

the&FDline)untilallcommandssenttotheinstrUment Hp-85’

are inteniay processed once~the instrument receives the

X chamter. K command options include: KO = Send EOI with last byte; hold off bus until com-

mands processed on X.

Kl = Do not send EOI with last byte; hold off bus until

7 commands processed on X.

K2 = Send EOI with last byte; do not hold off bus on X.

When the second statement is executed, the instrument will be placed in the K2 mode. In this mode, EOI will still be

transmitted at the end of the data string, but the bus holdoff mode w$l be disabled.

K3 = Send no EOI with last byte; do not hold off bus on X.

Upon power up, or after the instrument receives a DCL or

SDC co

condition.

The EOI line on the IEEE-488 bus provides a method to

mmand, the instrument will return to the default

Commands

Function (F]

positively identify the last byte in a multi-byte transfer sequence. Keep in mind that some controllers 1~4y on EOI to terminate their input sequences. In this case, suppressing EOI with the K command may cause the contr@er input sequence to hang unless other terminator sequences

Range CR)

are used.

The bus hold off mode allows the instrument to temporarily hold up bus operation when it receives the X character until

Calibrate (C

it processes all co mmands sent in the command string. The

purpose of the hold off is to ensure that the front end FETs

and relays are properly configured before taking a reading. Keep in mind that all bus o tivity associated with the hf

eration will cease--not just ac-

ode1 196. The advantage of this

Others

mode, enter the followmg statemats into the

FiEMOTE 707

‘OUTPUT 797 i r r KZX ’

Table 3-13. Bus Hold-off Times (Typical)

Bus Held-off on X for:

1OOmsec on DCV (FO), Ohms (F2) and Compensated Ohms (F7) 63Omsec on ACV (Fl), ACA (F4), DBV (F5) and DBA (F6) 16Omsec on DC4 (F3)

lOOmsec on most range conunands l7Omsec on 3OM0 (F2R6) and 34OMQ

(Fuv) ranges

638msec per range comman

(F’4 and Aa 0

donACV

9sec on most functions

IBSsec on 3OM0 (E?R6) and 3WMll 0 ranges

94msec to llOmsec depending on command sent lsec for selftest (JO) command

3-26

IEEE-488 PROGRAMMING

3.9.15 Terminator (Y)

The terminator sequence that~marks the end of the instmmerit’s data string or status word can be programmed by sending the Y command followed by an appropriate character. The default terminator sequence is the commonly

used carriage return, line feed (CR LF) sequence (YO). The

terminator will assume this default value upon power up, or after the inshxment receives a DCL or SDC command. Programmable terminators include:

YO=CRLF Yl=LFCR M=CR Y3 = LF Y4 = No terminator

HP-85 Progr amming Example--To reserve the default (CR

LF) terminator sequence, type the following lines into the computer.

REMOTE 707

OLITFUT 767j r i YBX ’

The format of UO status is shown in Figure 3-8. Note that the letters correspond to modes programmed by the respective device-dependent comman de.. The default values in the status word are also shown in Figure 3-8. Note that all returned values accept for those associated with the terminator correspond to the programmed numeric values. For example, if the instrument is presently in the R3 range, the second (R) byte in the status word wiJ.l correspond to an ASCII 3.

The Ul command allows access to Model ‘I.96 error condi-

tions in a similar manner. Once the sequence UlX is sent, the instrument will transmit the error conditions with the

format shown in Figure 3-9 the next time it is addressed

to talk in the normal manner. The error condition word will be sent only once each time the Ul command is transmitted. Note that the error condition word is a&ally a string of ASCII characters representing binary bit positions. An error condition is also flagged in the serial poll byte, and the instrument can be programmed to generate an SRQ when an enur condition OCCUIS. See paragraph 3.9.13. Note that all bits in the error condition word and the serial poll b e error bit~will be cleared when the word is read. In add? hon, SRQ~ op%r&ion will be restored after an error conditionby reading Ul.

When the second statement is executed, the normal terminator sequence will be reserved; the instrument will terminate each data string or status word~with a (CR LF).

3.9.16 Status (U)

The status command allows access to information con&m-

ing various operating modes and conditions of the Model

196. Status commands include:

LJO = Send machine status word. Ul = Send error conditions. UZ = List Translator words. U3 = Send a value indicating the buffer size. U4 = Send the average reading in the data stores. U5 = Send the lowest reading in the data store. U6 = Send the highest readiig in the data store. U7 = Send the present value (V). U8 = Send input switch status (front/rear).

When the command sequence UOX is transmitted, the instrument will transmit the status word instead of its normal data string the next time it is addressed to talk. The status word will be transmitted only once each time the UO command is given. To make sure that correct status i+ transmitted, the status word should be requested as soon

as possible after the con-man d is transmitted.

The various bits in the error condition word are des-

aibed as follows: TRIG ERROR-Set when the instrument receives a trigger

while it is still processing a reading from a previous trigger. SHORT TIME-Set when the instrument cannot run as fast

as the selected data store interval. BIG STRING-Set if more than a 10 character message is

sent using the display (D) command.

UNCAL-Set when EVROM memory fails the self test. Instrument calibration is invalid.

CAL LQCKED-Set when t@ng to &irate the instrmnent

with the calibration switch in the disable position. CONFLICT-Set when trying to calibrate the instrument

while it is in an improper state. (i.e. dB function). Translator Error (TRANSERR)-Set when any one of ten

possible Translator enors occur. Table 3-15 in pmagraph 3.10

lists and describes the Translator errors.

NO REMOTE-Set when a progamming command is received when REN is false.

IDDC-Set when an illegal device-dependent command

(IDDC), such as ElX is received (“El’ is illegal).

3-27

IEEE-408 PROG!%tblMlNG

FACTORY DEFAULT

1 0 0 0 0 0 00 1

196 A B F 0 J

K MM N PP

000000 4 3 6 00000

QQQQQQ R S

T WWWWW Y Z SW

,, :

0 0 011

CAL

MODEL NUMBER PREFIX (196)

A”To,oAL MWTIPLEX (A,

O=OIS*sl.ED

l=ENAsLEo

Re*DING MODE (B, O=AJD CONVERTER

l=DATA STORE SUFFER

FUNCTION (0 o=oc “OUS

,=*c VOLTS 2=OHMS 3=x CURRENT &-AC CURRENT

SELFTEST (.I) O=INACTI”E

l=ROM. RAM and E’PROM PASSED

2=E*PROM FAILED

RANGE (R,

Dcv *cv DCA

AU OHMS

OffSet

COmpenSated

ACVdS ~.KAdS O)I,?s

EXPONENTIAL FILTER (i-4) O=OISASLED ,=EN*BLED

3-28

Z=ENPISLED USING ZERO VALUE

cALIBRATlON SWITOH “=“lSARI F”

Figure 3-8. 00 Machine Status Word and Default Values

~_____ .,,

~,.,”

IEEE-488 PROGRAMMING

IDDCO--Set when an illegal device-dependent command

option (IDDCO) such as T9X is received (“9” is illegal).

NOTE

The corn lete command string will be ignored if an IDD P , JDDCO or no remote error occurs.

The U2 command lists the Translator words that have been

defined by the. operator. The list will be transmittedonly

once each time fhe command is received.

The U3 command allows the user to find out the current

defined size of the buffer. The buffer Size iFZ&olled by

the I command. When this command is transmitted, fhe

instrument will transmit the value the next time~it is ad-

dressed to talk. This information will be transnxi&d only

once each time the command is received. The U3 value will

not be cleared when read; thus, the U3. value is always

current.

The U4 command sends the average of all the readings that

are in the data store. The U5 conun~nd sends the lowest

reading in the data store and the U6 command sends the

highest. When any of these co mmands are transmit@$fhe

instrument will send the appropriate reading the next time

the instrurnent~is addressed to talk. A reading will only be

sent-once each time the appropriate command is received.

~gyni&on of U4, U5 and U6 will not occur until the buf-

PROGRAM

10 REMOTE 707

COMMENTS

Send remote enable.

xi DIM ABC401

30 UIUTPUT 7U7 ( L UBY’ y 40 DISP * ~mdlHBFGJKtltlN

PPQ~!aaP~RSTWWWl,lWY Z%‘” ~~~~~~~~~~ ~~~

50 EHTER~TWT; At:

, I Send UO command.

obtin uo stibls from instrument.

60 UISF-‘-A5

7U ENTER 707; RB

:m III% A$

Display UO status word.

~Get n&mal reading.

Display normal reading.

30 END

After eni+ng the program, run it by pressing the HP85 RUN key. The machine conditions of the Model 196 will be listed on the CRT display. To show that status is &ansn& ted only once, a normal reading is requested and displayed last.

3.9.17 Auto/Cal Multiplex (A)

The Model 196 has built-in multiplex routines that automatically calibrate and zero the instrument, so as to maintajn its high accura defeated, either through

2.25) or through one of the following comma$.s: A0 = Disable multiplex

Al = Enable multiplex

The multiplex routines can be

ant panel Program 6 (paragraph

The U7 command sends the present value. The value can

be a calibration value, or a zero value.

The US command sends a value that defines~ the status of

the input switch. A value of 0 indicates that the~front pariel

input terminals are selected, while a value of ~1 indicates

that the rear panel input terminals are selected.

HP-85 Progamming Example-Enter the following

statements into the computer to obtain and display the

machine status word (UO).

Upon power up or after a DCL or SDC command, the instrument will return to the default-condition.

HP-85 Programming Example-Disable multiplex by entering the following statements into the I-E-85:

REMOTE 707

OUTFUT 707; “AOXx 5

When the END LINE key is pressed the second time, the multiplexer routines will be disabled.

3-29

l=lRIG ERROR

rl=SHORT TIME

196 d/l k/l O/I O/i 0 0 0 O/l O/I O/I

I=CAL LOCKED’

I=CDNFLICT

I-TRANSERR 9

O/I O/I D/l

0 D/l O/I

I=lRANSERR23

ALUAYS ZERO,

O/I O/I O/I O/I O/I D/l ;, Oil

I=TRANSERRPI

I=TRAMSERR20

I-TRANSERRIS

LI=TRANSERR17

l:TRANSERR16

I-ND REMOTEA

I--IDDC

‘i

l=IrJOCO

LI=TRANSERRIk ~

l=TRANSERRl4

AlhAYS ZERO

IEEE-488 PROGRAMMING

3.9.18 Delay (IV)

The delay command controls the time interval that occurs horn the point the inslrument is triggered until it begins integration of the input signal. This feature is useful in situations where a specific time period must transpire to allcw an input signal to settle before measurement. During the delay period, the inputs multiplexing FETs ar@ switched on so the inshument is set to begin integration upon conclusion of the programmed delay period. A delay period can be programmed using the following command:

Here, n represents the delay value in milliseconds. The

range of programmable delay values is from Omsec to

600Oflmsec.

Examples: For a delay of 0.002sec send W2X. For a delay of 30.05sec send W3005OX. For a delay of 60sec send W6OOOOX.

Upon power up or after receivin the instrument will return to t

a DCL or SDC commtidj

a e default condition.

JO = Perform self-test.

Ifthe self-test is successful, the J byte in the UO status word

will be set to 1. If E’PROM fails, the message ‘VNCAL!’

will be displayed and the J b te in the Ul status word will

be set to 2. Ati EzPROM f a3

ore is also flagged~in thg Ul status word. If ROM and RAM fails, the instrument will lock up.

See paragra h 6.7.2 for more information on these tests and

recomme&tions to resolve a failure.

HP-85 Programming Example-Enter the following statements into the computer to perform the Model 196 self-test:

REMOTE 707

OUTPUT 707.: ’ s JOX” ’

When the END LINE key is pressed the second time, the

instrument erforms the self-test. If sUCcessful, the self-test

byte (J) in tK e UO~status word will be set to 1.

HP-85 Pmgr amming Example--To program a 25Omsec delay

period into the instrument, enter the following statements

into the computer:

REMOTE 707

OUTPUT 707; I’WZ5OX”

After the END LINE key is pressed the second time, the instrument will wait for 25Omsec after each triggered conversion before executing the next coversion period.

3.9.19 Self-Test (J)

The J command causes the instrument to perform tests it

automaticsJly performs upon power up. When the self-test command is given, the Model 196 perfor?ns the following tests:

1. ROM Test

2.RAMTest

3. EIPROM Test

J command parameters include:

3.9.20 Hit Button (H)

The hit button tually any front panel control sequence. Through the use of-the H command, the front panel programs may be entered through commands given over the bus. The H command is sent by sending the ASCII letter followed by a number representing a front panel control. These control numbers are shown in Figure 340.

E@ples:

H3x-Selects the ACA function. HOX-Selects the ACV function.

HP-85 Programming Example-Enter the following statements into the computer to place the instrument in the ohms function:

When the END LINEkey is pressed the second time, the instrument is placed in the ohms function.

command allows the user to emulate vir-

REMOTE 707

OUTPUT707j”HiX”

3-31

Figure 3-10. Hit Button Command Numbers

3.9.21 Display (D)

The display command controls the ASCII messages that

can be placed onto the Model 196 display. Messages are controlled with the following commands:

Da = DIsolav character “sT’, where “a” reoresents a orint~ble

A&II’ character. tip to 10 chkacters (&&ding blanks) may be sent.

D =~ Restores display back to normal.

3-32

Notes:

1. In order to have spaces preceding the beginning oft the message and between message words, use the @ sym-

bol to represent~each space. For example, to-display the

message “Model 196” starting at--the seconds display character (one space), send the following command string:

c d D@tlODEL@i=c5V’ 5

, .a

2. Spaces in a command string are ignored.

3. Sending a message that exceeds 10 characters will results with the big string error message being @splayed.

IEEE-488 PROGRAMMING

HP-85 Programmi ng Example-Enter the following statements into the computer to display the message “MODEL

196”:

REMOTE 707

WTFUT 7073 r r DWlOIIELCi96 X3 ’ :

HP-65 Programming Example-Enter the following statements into the computer to turn the internal filter off:

HEMITE 707

UUTPIUT 797; 6 G HMX 5

When the END LINE key is pressed the second time, the

When the END LINE key is pressed the sec+d time the internal filter will disabled. instrument model number will be displayed: Display operation may be returned to normal by entering the following statement:

OUTPUT 767; 6 6 I!:+~ ’

3.10 TRANSLATOR SOFTWARE

The built in Translator software allows the user to define his own words in place of Keithley’s defined device-

3.9.22 internal Filter (N)

dependent commands. One word can replace a single com-

mand or a string of commands. For example, the,word ACV

can be sent in place of Fl, and the word SETUP1 can be

In addition to the digital filter (P), a running average filter

sent in place of F3R1T2S~ZllJOMZFl5. Also, Keithley cornis used to provide additional filtering when making high mands can be translated to emulate functions of other units. resolution and high sensitivity measurements. The interml filter is controlled by the following commands:

For exam$e, the~word RA, which is used by H-P to select

~autorange, can be sent in place of RO. There are Yertain

words and characters that cannot be used as defined NO = Internal filter off. Nl = Internal filter on.

Translator words. These reserved words and character make

;!4;he Translator software syntax and are listed in Table

The factory default condition of the internal filter is Nl

(enabled).

Table 3-14. Translator Reserved Words and Character

Word/Character Description

ALIAS

Used at~the beginning of a command string to define Translator words. Used to terminate the Translator string (one space must precede it).

Used to define wild card Translator words. Values sent with a wild card

Translator word select options of the equivalent DDC. Tells the Model 196 to recognize Translator words. Tells the Model 196 to only recognize the Keithley device-dependent commands.

SAVE LET FORGET

Saves~Translator Words as power up default. Used to list the Translator words. Used to purge Translator words from memory.

3-33

3.10.1 Translator Format

The basic format for defining a Translator word is shown in the following example command St&g, whi&d&ines the word SEZIJR as a substitute for FlROX.

‘ALIAS sETuPl FlROX ;”

Where: ALIAS is a reserved word that precedes the Translator

word. SETUPl is the desired Translator word. FlROX is the Keithley command string.

is a reserved character necessary to tetiate the

; Tran%lahx stig.

(spaces) must be used to separate words and the “;” character.

When SETUFl is sent over the IEEE-488 bus, the in&ument will go to the ACV function (Fl) and enable autorange

Translator words that contain conflicting device-dependents command.?., such as Fl and F2, can be defined. When sending the comma

d word over the bus, the device-dependent command that was last entered will prevail. For example, sending a Translator word in place of FOFYX will place the

instrument in the Fl function.

Notes:

1. Trying to define a Translator word that already exists will cause an error message to be displayed briefly. Thatk Translator word will retain its original definition.

2. A.Translatoi word cannoi exceed 31 characters.

3. The Translator buffer can hold approximately 100 B-character Translator words.

4. The character X and $ cannot be used in Translator words.

5. The Model 196 will not recognize an undefined Translator word sent over the bus.

6. A valid Translator word sent over the bus while the instrument is in the OLD mode will not be recognized.

However, the instrument will try to execute (on the next X) the letters and numbers of the word as if they were

device-dependent commaqds.~ To avoid this problem, it

is recommended that NEW be sent before trying to execu@Translator words. See paragraph 3.10.3 for an explanation oft NEW and OLD.

7. Translator error messages are listed and described in

Table 3-7.5.

HP-85 Programming Example-Enter the following pro&ati into the c&i@uter &define a Translator word

(SETUPI) to emulate-the command string FIROX:

REMOTE 7M7

C~UTPLlT767r’LALIASSETlJPiFlROXi’~

UUTFUT707; ‘rSETUP1’!

Table 3-15. Translator Error Messages

Display Message Explanation

Example Error String

TRANSERR 9 No more memory left for Translator words. TRANSERR14 Use of more than one ALIAS in a definition. TRANSERRl5 Translator word exceeds 31 characters.

“ALIAS TESTI l?lX ALIAS TEST2 RLX ;‘I ‘RUAS ITwNKTHIs1sTHIRpITw OCHARACT

ERS! FIX ;I’

TRANSERRl6 Use of an X in a Translator word.

“ALIAS XRAY FIX ;”

TRANSFERl7 Trying to define a Translator word ~&at alre@y “ALIAS SETUl? FIX ;”

exists. The second string in the example is the “ALJAS SETUP RlX ;”

error shing. TRANSERRB Use of a $ in a Translator word. ‘ALIAS $200 FCC;” TRANSERRl9 Sending the ; character. TRANSERR20 Use of LIST in a Translator definition. TRANSERR21 Use of FORGET in a Translator_definition. TRANSEKQ.3 Use of SAVE in a Translator definition.

n.,, kIAS DOG FlX LIST ;”

“ALIAS DOG FJX FORGET ;” ‘NJAS DOG FIX SAVE ;”

3-34

IEEE-488 PROGAAMMlNG

When END LlNE is pressed the second time, the Translator word will be defined to emulate the Keithley command string. When END LlNE is pressed the third time, the in-

strument will go to the ACV function (n) and enable autorange (RO).

3.10.2 Wild Card ($)

An advanced feature of Translator software is its wild card capabilities. By using the reserved character~“$‘: the same basic Translator word can beg used to select all options of a command. With this feature, a DDC~ option number is sent with the wild card Translator word. The format for

using the wild card is shown in the following wple, which defines the word FUNCTION as a substitute for the F command:

“ALIAS FUNCTION F$X ;”

“FLlNCl-ION ~1” “FUNCTION 2’

The first statement defines FUNCTION as the wild card Translator word for the F command. The wild card ($) will allow any w&d option number of the F command (0 through 8) to be sent with the word. The second statemtint which is the substifute for the Fl command, will place the instrument in the ACV function. The third statement is a substitute for the F2 command, and will place the instrument in the ohms function.

Notes:

1. When sending a wild card Translator word over the bus,

there must be a space between the Translator word and the option number.

2. If a wild card Translator word is sent without an option

number, the instrument will default to option 0.

3.10.3 NEW and OLD

NEW is a reserved word that tells the instrument that the

ensuing commands may be defined Translator words. The instrument will then respond to the Transistor words as well as Keithley device-dependent comman ds. The re-

served word ALIAS automatically places the instrument in the NEW mode. NEW is also used to combine Translator words and is explained in paragraph 3.10.4.

OLD is a reserved word that preventsthe instrument from tisponding to the defined Translator words. In this mode, only the Keithley device-dependent commands will be recognized cwer the bus.

HP-85 Programming Example-Enter the following statements into the computer to place the instrument in the NEW mode:

~- REMOTE 707

OUTPUT 7137; s ‘HEW ’

When ENlILINEis pressed the second time, the instru-

ment~wiu go into the NEW mode.

3.10.4 Combining Translator Words

Existing Translator words can be combined resulting in a

Translator word that contains the cow ds of the two (or

more) combined words. For example, exist&~ Translator

words SETUP and SETU2 can be combined and named SETUPB When SETUP3 is sent over the bus, the commands of both SETUP1 and SETUP2 will be executed. The f-t fir combining Translator words is shown in the

following e+nple:

“ALIAS SETUP3 NEW SETUP1 NEW SETUP2 ;”

HP-85 Pmgramming Example-Enter the following pro-

gram to define a wild card Translator word to emulate the P (filter) command.

REMOTE 707

OUTPUT7Bij rrALIASFILTERP$Xj”

OUTPUT707; 11FILTER20”

The second statement defines FIUER as the wild card Translator word for the P comman

d. The third statement

enables the filter with a filter value of 20.

Where:

SETUP3 is the new Translator word. SETUPl and SETUP2 are words to be combined.

NEW is a reserved word that tells the instrument that

SETUFl and SETUP2 are Translator words and not Keithky

device-dependent commands.

Even though the two words were combined to form

SETUP3, SETUPI and SETUI’2 still exist as valid Translator

words.

3-35

IEEi-488 PROGRAMMING

Wild card Translator words can also be combbied with other

Translator words. The option number used with the new word will apply only to the fir& wild card word in the string. For example, assume that FILTER (emulating the P command) and FUNCTION (emulating the F command) are wild card Translator words that are to be combined with the normal Translator word SETUPl. The format might look like this:

“ALIAS TEST NEW SETUPl NEW FUNCTION

NEWFIU’ER;”

The new Translator word is TEST. Whenever TEST is sent, the option value sent with that word will only affect futiction since FUNCTION is the first wild card command in the string. For example, TEST might be sent~oyq the bus in the following format:

‘TEST 3”

The “3” in the command string will ony affect the FUNC:

TION command. In this example the instrument will be

placed in the DCA function (F3). Since the FILTER command does not have an assigned option value (due to its position in the s’xing), it will default to 0 (disable).

HP-85 Progr

amming Example--The following program will create two Translator words and then combine them to form a third Translator word:

REllnTE 707

OUTPUT707i”ALIASSETUPlFlX I)’

_._ _-

The second and third propam statementsdefine the two

TraiBlator words. When END LINE is pressed a fourth time, the two words combine to form the new word

(SETur3).

Where:

SETUP3 is the new Translator word.

SETUl?l and SETUP2 are the existing words. PlZlX is the Keithley IEEE command string. NEW tells the instrument that SETUPl and SETUP2 are

Translator words.

When the Translator word SETUP3 is asserted over the bus,

the commands of the two Translator words and the Keithley IEEE command string will be executed.

HP-85 FYogr amming Example-The following program will

tieate’two TIanslator words and then combine them with

a Keithley IEEE cornman< string to form a new Translator

woid:

REMOTE 707 OlJTPUT~707i”ALIkSSETUPl FiX i” OUTPU~707i1’ALIASSETUP~R0Xi”

OUTPlJT707;“ALIASSETUP3t4EWSETUPi

N3l SETUP2 PlZlX i”

The second and third statements create two Translator words. When END LINE is pressed the fourth time, the two Translator words are combined to form the word

slguP3:

3.10.8 Executing Translator Words and Keithley IEEE Commands

Translator words (includmg wild card words) and Keithley IEEE commands can be executed in the same command string. The fortit for doing this is demonstrated in the following examples:

“SETUR Mzy(”

TlJNCIlON 2 PEW

3.10.5 Combining Translator Words With Keithley IEEE-488 Commands

One or more existing Translator words (iicluding wild card words) can be combined with Keithley IEEE commands resulting in a Translator word that contain! the commands of the Translator words and the Keithley IEEE comqqds.

The format for cotibirdng Translator words with~I+ithley

IEEE commands is shown in the following example:

“ALIAS SETUP3 NEW SETUPI NFW SETUi=Y~PlZlX i”

3-36

When the first command string is sent over the bus, the

commands in SETUPl and the Keithley IEEE commands will be executed. When the second string is sent, the second option of the wild card FUNCTION command and the Keithley IEEE commands will be executed.

Hp-85 Programming Example--The following program will’

as+ the commands of an existing Translator word and the,$+dard Keifhley IEEE commands over the bus:

;

REMOTE 707

When END LINE is pressed the second time, the corn-

man& of SETUP1 and the Keithky IEEE comman

ds to the computer. When END LINE is pressed a fourth time,

(FElX) will be sent over the bus.

The second and third statements will send the word list the Translator words will be displayed.

3.10.7 SAVE

Translator words can be remembered by the instrument as power up default words by sending the reserved word SAVE. If SAK is not Sent, Translator words will be lost when the instrument is turned off; Program 37 (Reset) is run, or an SDC, DCL or M is sent over the bti.

When SAVE is sent, the instrument also remembers if it was in NEW or OLD. Jf the instrument is in NEW when

SAVE is sent, it ~wiu power up in NEW. If the instrument is in OLD when SAVE is sent, it will power up in OLD.

HP-85 Pmgr words already defined, enter the following statements into the computer to retain them as power up default words:

When END LINE is pressed the second time, current

Translator words will become power up default words.

amming Example--with one or more Translator

REMOTE 787

OUTPUT707;*LSA’JE”

3.10.9 FORGET

FORGET is a reserved word that is used to purge all Translator words from temporary memory. However, Trarislator words that were saved in ElPROM by the SAVE command will again Je ~qailable after power to the instrument is cycled, Program 37 (Reset) is RUN, or DCL, SDC or Ul is sent over the bus.

To u e Translator words from EY’ROM, first send the FO iis G T comnd and then send the SAVE command.

HP-85 Programming Example-Enter the following

statements into the computer to purge all Translator words

from temporary memory:

REMOTE 707

OUTPIJT 707; * r FORGET’ p

When ENDLINE is pressed the second time, the Translator words are purged from temporq memory.

3.10.8 LIST

LIST is a reserved word that can be used to lit the existing

Translator words stored in temporary memory. The most

recent defined word will be listed first.

Notes:

1. The UZ command can also be used to list the Translator words (see paragraph 3.9.16).

2. If there are no Translator words in memory, nothing will be displayed when the list is requested.

HP-85 Programming Example--With Trtilator words already defined, enter he following program statements to list them:

REMUTE7CI7 ~~~

OlJTPUTiEVi‘~LIST’~

ENTE~R 707; A5

DISP A$

3.11 BUS DATA TRANSMISSION TIMES

A primary consideration isthe length of time it takes to obtain a reading once the instrument is triggered to make a conversion. The length of time will vary somewhat depending on the selected function and higer mode. Table

3-16 give-s typical times.

Table a-16. Trigger To Reading-Ready Times

(DCV Function)

Configuratioa

SOAOGlNOTIX

Mode

Maximum Reading Rate (3%d)

SL4OGlNOTlX

S2AOGlNOTlX

S3AlGlNOTlX

4Md 5Yzd

6Yzd (internal filter off)

S3AlGlNlTlX

6%d (internal filter on)

“Commands not listed are at factory default.

Tie (typical)

6msec

Smec

24msec

106msec

3.3sec

3-3713-38

SECTION 4

PERFORMANCE VERIFICATION

4.1 INTRODUCTION

The procedures outlined in this section may be used to

verify that the instrument is operating wifhin the limits stated in the specifications at the front of this manual. Performance verification may be performed when the instrument is first received to ensure that no damage or misadjustment has occurred during shipment. Verification may also be performed whenever there is a question of instru-

ment accuracy, or following calibration, if desired.

NOTE

If the instrument is still under warranty (less than

1 year from the date of shioment). and its oerfonn-

ante falls outside the specified range, contact your Keithley representative or the factory to determine the correct course of action.

4.2 ENVIRONMENTAL CONDITIONS

All measurements should be made at 18 - 28’C (65~ 182°F) and at less than 80% relative humidity.

4.3 INITIAL CONDITIONS

The Model 196 must be turned on and allowed to warm up for at least two hours before beginning the verfication procedures. If the instrument has been subject to extremes of temperature (outside the range specified in paragraph

4.2), additional time should be allowed for internal temperatmes~ to reach normal operating temperature. Typically, it takes one additional hour to stabilize a unit that is 10°C (18°F) outside the specified temperature range.

4.4 RECOMMENDED TEST EQUIPMENT

Table 4-l lists all test equipment required for verification. Alternate equipment may be used as long as the substitute equipment has specifications at least as good as those listed in the table.

NOTE

The verification limits in this section do not include test equipment tolerance.

Table 4-l. Recommended Test Equipment

Description I Specifications DC Voltage Calibrator

AC Voltage Calibrator AC Power Amplifier

300mV, 3V, 3OV, 3OOV ranges *15ppm. 3OOmV, 3V, 30V ranges; 2OHz H.l%; 50Hz-20kHz 9.02%; 1OOkHz M.33%. 3OOV range: 2OHz B3.12%; 5OHz-2OkHr M.04%;

lookHz~.1%

Resistance Calibrator AC-DC Current Calibrator 300~~3A n&es +..d3’% DC, +o.l% AC to 5kHz (at

3COQ-3MQ ranges il5ppm; 30MQ i32ppm; 300MR ranee~B25nnm

full scale output)

4-I

PERFORMANCE VERIFICATION

4.5 VERIFICATION PROCEDURES

The following paragraphs contain procedures for verifying

the one year accuracy specifications of the instniment,~ at 5%d resolutiofi, for each of the five mea&@ fticiions: DC volts, TRMS AC volts, ohms, TRMS AC amps,~ and DC

amps. These procedures are intended for use only by qualified personnel using accurate and reliable test equipment. If the instrument is out of specifications and not under warranty, refer to Section 6 for calibration procedur+

WARNING

The maximum common-mode voltage (voltage

between inout low and chassis aroundt is 5OOV. Exceeding this value may cause-a breakdown in

insulatlon, creating a shock hazard. Some of the procedures in this-section may expose the user to dangerous voltages. Use standard safety precautions when such dangerous voltages are encountered.

4.5.1 DC Volts Verification

With the Model 196 set tom5Yzd resolution, verify the DC volts function as follows:

see that~ the reading for each range is within the limits listed in the table.

7. Repeat the procedure for each of the mnges with negative voltages.

Table 4-2. Limits for DC Volta Verification

196

DCV Range DC Voltage

300mV

3 v

30 v

300 v

Applied

Allowable Readings

I I

3OO.OOOmV 299.974

3.00000 TV 2.99987

30.0000 v 29.9973

300.000 v 299.970

(wto 28T)

to 300.026

to 3.00013 to 30.0027 to 300.030

Figure 4-1. Connections for DC Volts Verification

CAUTION Do not exceed 300V between the input HI and LO terminals or damage to the instrument may occur.

1. Select the DCV function and autorange.

2. Cdiinect the DC voltage calibrator to the Model ‘I96 as shown in Figure 41.

3. Set the calibrator to OV and enable zero on the Model 19fYVerify that the display is reading OOO.OOOmV ~2~ counts.

NOTE

Low measurement techniques should be used when checking the 3oOmV DC range. Refer to paragraph 2.6.5 for low level measurement considerations.

4. Set the calibrator to output +3OOmV and verify that the

reading is within the limits listed in Table 4-Z.

5. Disable zero and leave it disabIed for the remainder of

the DCV verification procedure.

6. Check the 3V, 3W, and 3OOV ranges by applying the

respective DC voltage levels listed in Table 42. VeqJo

4.5.2 TRMS AC Volts Verification

With the instrument set to 5%d resolution, perform the following procedure to verify the AC volts function:

CAUTION Do not exceed 3OOV RMS 425V peak lOV*Hr between the input HI and LO terminals or instrument damage may occur.

1. Select the ACV function and &orange. Do not use zero to cancel the offset in this procedure. Turn zero off, if it is enabled.

2. Connect the AC calibrator to the Model 196 as shown in Figure 4-2.

3. Set the calibrator to output 29OmV at a frequency of 2OHz and verify that the reading is within the liits listed in

Table 4-3.

4. Repeat the 290mV measurement at the other frequencies specified in Table 43.

5. Repeat the~piocedure for the 3V, 30V and 300V ranges by applying the respective AC voltages listed in Table 4X%.

Check to see that the reading for each range is within the limits listed in the table.

4-2

Table 4-3. Limits for TRMS AC Volts Verification

PERFORMANCE VERIFICATION

I96

ACV Rang

300mV

3 v

30 v

300 v

*Do not apply 290V at 1OOkHz to the input. This exceeds the V-Hz limit~of the instrument.

Maximum TRMS AC volt input at XlOkHz is 1OOV On the 300V range, allowable readings witYq 1OOV @ 1OOkHz applied to~~the input are 98.200 to 101.800. See paragraph 2.6.7 for clarification of the V*Hz specification.

Applied

AC Voltagg

29O.OOOmV

2.9OOOOV

29.oooov

29O.ooOV

2OH~zP 5oHz

284.100 289.030 29soo

2.84100 to

2.95900~ 2.90970

28.4100 = 28.9030 to-

29;5900 29&o

284.100 289.030 to

295.900 290.970

Allowat

to-

290.970

2.89030 to

289.465 289.465 288.640 283.900 to

Z&35 29&35 291.360 29&Xl

12.89465 1 2.89465 1 2.88930 I 2.85350 I

2.9:35 2.9%35 2.9%0 2.9+&O

28.9465 28.9465 28.8640 28.5350

29.0535 29.0535 29.1360 29.4650

I to I to I tom I to I

..CAUT!ON

Do not exceed 425V peak or 3OOV RMS between

the input HI and LO terminals or damage to the

instrument may occur.

INPUT AMPLIFIER 1 CALIBRATOR

LO MODEL 5215A,MODEL 5200A

Figure 4-2. Connections for TRMS AC Volts

Verification

POWER ‘AC VOLTAGE

4.5.3 Ohms Verification

With the Model 196 set to 5%d resolution, verify the ohms function as follows:

1. Select the ohms function and autorange.

2. Using Kelvin test leads (such as the Keithley Model 1611) connect the resistance calibrator to the Model 196 as shown in Figure 43.

3. Set the caliirator to the SHORT position and enable zero on the Model 196. Verify that the display reads 000.000.

4. Set-the calibrator to output 19OQ and verify that the

~--reading is within the limits listed instable 44.

5. Disable zero and leave it disabled for the remainder of the ohms verification procedure.

6. Utilizing Figures 43 and 44, check the 3kQ through XlOMa ranges by applying the respective resistance levels listed in Table 4-4. Verify that the readings~are within the limits listed ins the table.

~~~

4-3

PERFORMANCE VERIFICATION

Table 4-4. Limits for Ohms Verification

tiODEL 196

196 Ran e

300 n

3kQ

30 kfl

300 kQ

3Ml-J

3OMQ

3OOMQ

OUTPUT HI

=SENSE HI

SENSE LO

OUTPUT LO’

set up

Figure 4-3 Figure 4-3 Figure 43 Figure 4-4 Figure 4-4 Figure 44 Figure 4-4

RESIST~ANCE CALIBRATOR

tiODEL StSOA

Figure 4-3. Connections for Ohms Verification

(300n--3OkQ Range)

OUTPUT HI

MODEL 196

CABLE

Applied

Resistance

190.000 61

1.90000 kQ

19.0000 k61

190.000 kdl

1.9OoOOMQ

19.OOOOMfl lOO.OOOMQ

Plowable Readings

(WC to 28T)

189979 to 190.021

1.89985 to I.90015

18.9985~ to 19.OGl5 X39.958 to 190.042

1.89958 to 1.90042

18.9808~ to 19.0192

97.998 to 102.002

~4.5.4 DC Current Verification

With the instrument set to 5%d resolution, verify the DC current function as follows:

CAUTION Do not exceed 3A to the AMPS and LO input terminals or the rear panel current fuse will blow.

1. Select the DC4 function and autorange.

2. Conned~the DC current calibration source to the Model 196 as shown in Figure 45.

3. Set the calibration source to output +3OOfi and verify that the reading is within the liits listed in Table 45.

4. Repeat the procedure for the 3mA,3OmA, 3OOmA and

3A ranges by applying the respective DC current levels listed in Table 45. Check to see that the reading for each range is within the limits listed in the table.

5. Repeat the procedure for each of the ranges with

negative current levels.

RESISTANCE

CALIBRATOR

MODEL 5450A

OUTPUT LO

Figure 4-4. Connections for Ohms Verification

(300kQ-300MO Ranges)

4-4

Table 4-5. Limits for DC Current Verification

Applied

l96 Range

300 PA

3m.4

3om.4

3oomA

DC Current

300.000 pA

3.ooooonL4 3o.ocKlonL4

300.000!&4

3.OOOOO A

299.710 to 300.290

2.99840 to 3.00160

29.9840 to 30.0160

299.84Oto 300.160

2.99720 to 3.00280

L CURRENT Lo

CALIBRATOR

MODEL 2500E ,,, T MODEL 5440A

INPUT

Lo DC VOLTAGE

CALIBRATOR

PERFORMANCE VERIFICATION

2. Connect the AC current calibratiori source to the Model 196 as shown in Figure 4-6.

3. Set the calibration source to output 3006 at a frequency of 20Hz and verify that the reading is within the limits listed in Table 4-6.

4. Repeat the 3OOd measurement at the other frequencies

specified in Table 4-6.

5. Repeat the procedure for the 3mA, 3Om.4, 3OOmA and 3A ranges by applying the respective AC current levels listed in Table 4-6. Check to see that the reading for each range is within the limits listed in the table.

Figure 4-5. Connections for DC Current Verification

4.55 TRMS AC Current Verification

With the instrument set for 5%d resolution, verify the AC current function as follows:

CAUTION Do not exceed 3A to the AMPS and LO input terminals or the rear panel current fuse will blow.

1. Select the ACA function and autorange. Do not use zero to cancel the offset in this procedure.

Table 4-6. Limits for AC Current Verification

L CURRENT Lo

CALIBRATOR

MODEL XOOE HI 7 MODEL 5200A

INPUT

Lo AC VOLTAGE

CALIBRATOR

-I

Figure 4-6. Connections for TRMS AC Current

Verification

4-514-6

SECTION 5

PRINCIPLES OF OPERATION

5.1 INTRODUCTION

This section contains an overall functional desaiption of

the Model 196. Detailed schematics and component location drawings are located at the end of $s instr@on manual.

5.2 OVERALL FUNCTIONAL DESCRIPTION

A simplified block diagram of the Model 196 is shown in Figure 5-1. The instrument may be divided into two sections: analog and digital circuitry. The analog and digital sections are electrically isolated from each other by the use of pulse transformers for control and communications. Separate~power supplies for the analog and digital secfiotis ensure proper isolation.

The analog section consists of the signal condition&g cir-

cuits, multiplexer, input amplifier, A/D converter and con-

trol circuitry. The heart of the digital sectioq is 6FBO9

microprocessor that supervises the entire operation of the instrument. Additional digital circuitry includes the diipl<~ and IEEE-488 interface.

5.3 ANALOG CIRCUITRY

The detailed circuitry of the Model 196 analog section is located on schematic diagram number 196-126.

Divided by 10 on the 30V range. Divided by I.00 on the 300V range.

On the 30V range, Ql3 is on and 43 is off routing the input %ignaJ in the multiplexer (Q35). On the 3OOV range, 413 is off and Q3 is on routing the input signal to the multiplexer (Q35). On the 3OOmV and 3V ranges, the input signal is removed from the resistor divider network (Ql.3 and Q3 off) and applies directly to the multiplexer thrdugh Kl and RI?.

ACV

The basic steps involved in ACV conditioning are as follows:

1. Relay K4 applies the ACV input to the gain circuitry. Here the signal undergoes a gain factor of 10 (3OOmV range),

1 (3V range), I.00 (30V range) or WIIO (300V range).

2. The signal is then applied to the TRMS converter (U27) where the AC si& is converted to a DC signal.

3. The DC signal is then applied to the multiplexer.

On the 3OOmV and 3V ranges, the signal is routed through relay K5 and buffer U28A. On the 3V range, the signal proceeds through analog switch LJZlC and buffer U26B before being applied to the TRMS converter (U27). On the 3OOmV range, the signal is detoured through analog switch UZlA to UZSB which is configured as a Xl0 amplifier. The amplified signal then proceeds through analog switch UZlB and buffer U26B to the TRMS converter (U27).

5.3.1 Input Signal Conditioning

Signal conditioning circui~~modjfie~ the input to a signal that is usable by the Model 196 and applies that signal to the multiplexer.

DCV

Signal conditioning fork the 30V and 300V ranges is performed by resistor divider network Rl7. On these ranges, Kl and K2 are open, and the divider network is connected to signal ground through Qll vd U22A. The following attenuation of the input signal is provided:

J.n the 30V range, the signal is applied to U26A. Because analog~switch U23C is open on this range, amplifier U26A has a feedback resistance of 1lBkO (R32) which results in a gain factor of 1110. The divided signal is then routed through analog switch U23B and buffer IJ26B to the TRMS converter (WY).

On the 300V range, the signal is applied to U26A. Because analog switch U23C is closed on this range, amplifier U26A has a feedback resistance of 118kn (l732) in parallel with l3kn (RZ4), resulting in a gain factor qf 1/lIlO. The divided

~signal is then routed through analog switch U23B and buf-

fer U26B to the TRMS converter (U27).

5-l

PRINCIPLES OF OPERATION

.----------~---__-- ---_----,---

INPUT CONOITIONlNG

DCV

ATTENUATION/

n REF RESISTORS

INTERFACE

INPUT A/D

AMPLIFIER

+ /p

ANALOG

DIGITAL

FRONT PANEL

BUTTONS

CONVERTER

Figure 5-l. Overall Block Diagram

OHMS

300kQ range: R17A I R17C (IOOkQ) 3M61 range: @7A II Rl7B (lMQ)

Resistance measurements are made using the ratiometric

30MlI and 3OOMQ ranges R37C (1OMQ) technique (see Figure 5-Z). When the resistance function is selected, a series circuit is formed between the ohms source, a reference resistor and the external unknown resistance. A cant flows through the reference resistor and the unknown resistance. Since this current is common

By ~easwing the four inputs to the A/D converter the

unknown resistance can be computed by the

microprocessor using this equation: to both resistances, the value of the unknown resistance can be calculated by measuring the voltage across ale reference resistor and the voltage across~the unknown Rx T resistance.

The following ohms reference resistors are used (see Figure 5-3).

For the 3OOQ orange VQ SENSE HI and VQ SENSE LO are

a&ally multipled by a factor of 10 in the input buffer

circuit. 3OOQ and 3kQ ranges: R26 (2W) 3OkQ range: RZ3~ (3Okfl)

DISPLAY

i=‘.&(Vtl SENSE HI - VQ SENSE IQ)

vnREFHl- VlaREFLO

5-2

PRINCIPLES OF OPERATION

Protection on the ohms ranges is accomplished by RTl, Q9 Since the voltage is sensed across the combined resistance and Ql6. For an input voltage applied to the Q input ter- of R,, Rx and Q; considerable error can be introduced into minals, Q9 and Ql6 clamp the voltage to the reference the reading. To use a 4-terminal connection, a second set resistors toasafelimit.RTllimitsthecumnttoQ9amdQ16. of leads (R2 and R3) are connected to the unknown

resistance. The amount of current through R2 and R3 is

much smaller than the current through Rl and R4. Thus, The Model 196 is equipped to make Z- or 4.-terminal resis- the voltage seen by the instrument is much closer to the tance measurements. Generally 4-terminal measurements actoal value across the measured resistance, minimizing the should be made on the 3003 range because the relatively error.

large output current can develop a significantvoltage across

the test leads, affecting measurement accuracy.

DCA and ACA Figure 5-2 shows the equivalent circuit of the input circuit. The resistor current shunt network R28 is configured so that

Rx is the unknown measured resistance and Rl, R2, R3 and a full scale current input will result in a 3oOmV drop across R4 represent the test lead resistance. R2 and R3 are connetted only during 4-terminal measurements. When using a 2-terminal configuration, all the current flows through the

the network on all current ranges. For DCA, this voltage

is routed to the multiplexer through analog switch U24B.

For ACA, the signal is routed through lJ2m~o Xl0 ampliser test leads Rl and R4. If Rx has a low value, the amountof~ U28B. The amplifier signal then travels through analog voltage developed across the test leads can be significant. switch U2lB and buffer U26B to the TRMS ConVerter. The

converted DC signal is then routed to the multiplexer.

RREF l

1 in REF HI I

I I

; Vn REF LO I

I I I0

iSENSE HI

iSENSE LO I

FRONT PANEL ;

CONNECTOR

INPUT;

Jv&

r----SENSE1

I R3 I

ME c i

L---JSENSEl vn

ALL

RX = RREF. cvn TENSE HI - vn SENSE Ed)

“,’ I

I I I

I I

LO I

I I I

INPUTI

LO I I

vn REF HI - vn REF ~0

Figure 5-2. Input Configuration During 2 and 4-Terminal Resistance Measurement

5-3

PRINCIPLES OF OPERATION

REFERENCE RESISTORS

\ II SENSE LO /

INPUT

01;

R17A

IOMfl

E HI

a13

R17B Llllnn

R17C

110.95kn

ai1

> TO a30 OF tlULTIPLEXER

>TO U22B OF RULTIPLEXER

R26

Loozkn

n REF LO

(3oon. 3kn I

n REF HI

( 30kn 1

>V~U35 OF

MULTIPLEXER

>TO U24A OF

MULTIPLEXER

TO U240 OF

>WJ‘TIPLEXER

u220

n REF LO

(300kn - soonn I >wJLTIPLEXER

TO a34 OFT

INPUT

\ LO

RREF. (Vn SENSE HI - Vn SENSE LO)

RX =

vn REF HI - vn REF LO

Figure 5-3. Resistance Measurement Simplified Circuitry

5.3.2 Multiplexer

The multiplexer circuitry selectsamong the var+us signals that xe part of the Model 196 measurement cycle and connects them to the input~buffer amplifier. Figure 5-4 shows a simplified schematic of the multiplexer circuitry The Front/Rear INPUT switch detector TJ75B is not part of a measurement cycle.

Figure 5-5 shows the general switching phases for the various signals. During each phase, an integration is per-

5-4

formed by the A/D converter, and the resultant data is used by the microprocessor to calculate the fiial reading.

The precharge amplifier (UZOB) is momentarily selected by

Q31 just before signal FET 430 is activated. The purpose

of the precharge amplifier is to get the signal seen by the

_ mput buffer amplifier closer to the actual input~~at signal

FET Q30: The precharge ampliier also provides the drive

to keep the FE% on until turned off by the control circuitry.

PRINCIPLES OF OPERATION

SIGNAL (SOOsdOC. 3VDC)

II SENSE HI

PRECHARGE

SIGNAL (DCA)

il REF LO (3Okn)

U24E

Q30

031

II SENSE LO

ZERO (3OV)

n REF Lo (3ook-3ootm)

SIGNAL ( BOVDC, 300VDC)

n REF HI

Figure 5-4. JFET Multiplexer

U22A

012

033

03s

5-5

PFilNClPLES OF OPERATION

REFERENCE REFERENCE

PHASE PHASE

II REF HI

PHASE

XL xl/

L L

SIGNAL SIGNAL

PHASE PHASE

J/ J/

ZERO ZERO

PHASE PHASE

J/ J/

CALCULATE CALCULATE A READING A READING

fT REF LO fT REF LO

PHASE PHASE

.L .L

II SENSE HI II SENSE HI

PHASE PHASE

XL XL

II SENSE LO II SENSE LO

PHASE PHASE

\1 \1

CALCULATE CALCULATE A READING A READING

5-6

A. TYPICAL YDLTAGE AND A. TYPICAL YOLTAGE AND 8. TYPICAL RESISTANCE MEASUREMENTS 8. TYPICAL RESISTANCE MEASUREMENTS

CURRENT HEASUREflENlS CURRENT HEASUREflENlS

Figure 5-5. hlutliplexer Phases

PRINCIPLES OF OPERATION

5.3.3 +2.1V Reference Source

Voltage and current measurements are based on comparing the unknown signal with an internal +&lV reference

voltage source. During each measurement cycle, the

unknown signal is sampled and then compared with signal common and the +2.1V reference values.

U34 provides a highly stable +6.95V reference, while Ul3

and RlO provide a constant current to minimize zener voltage variations. R36 and R37 divide down the +6.95V value to the final +t.lV reference voltage.

5.3.4 input Buffer Amplifier

The input buf The input buffer amplifier provides isolation between the input signal ana tne x/u converter. u41 pro\ input signal and the A/D converter. 441 provides the low noise, high impedance FET input for amplif noise, high impedance FET input for amplifier U35. The amplifier can be configured for Xl or X10 gain amplifier can be configured for Xl or X10 gain with R41 and R42 acting as the feedback network. Whel R42 acting as the feedback network. When Xl gain is selected by the mipprocessor, feedback is 101 selected by the mipprocessor, feedback is routed through pin 12 of the analog switch U44A. At Xl0 ga pin 12 of the analog switch U44A. At Xl0 gain, feedback is routed through pin I3 of~the multiplex switc is routed through pin I3 of~the multiplex switch. Amplifier gain configurations for the various function gain configurations for the various functions tid ranges

are listed in Table 5-l. are listed in Table 5-l.

Table 5-1. Input Buffer Amplifier (U35) Gain

5.4 AID CONVERTER

The Model 196 uses a tionstant~ frequency, variable pulse

width, analog-to-dig@ converter. A simplified schematic of t~he ~A@ used in &he Model 196 is shown in Figure 5-6.

The charge balance phase begins when~ the input enable/

disable line is set high. This occurs at the end of a softwaregenerated delay period thatallows the signal to settle after the appropriate multiplexer FET is turned on. Once the input + Fabled, the sign+ from the buffer amplifier is added to the level shift current applied through RllC and RllD or RllC only. In this manner, the i3.03V bipolar signal from the buffer amplifier is converted to a unipolar signal that can be integrated.

The integrator is made up of Ql, Ul9 and C32. When the

input to the integrator is applied, the integrator output ramps up until its voltage is slightly higher than the voltage applied to the inverting input of ~the duty cycle comparator (U5A). The charge balance current, whose duty cycle is pro-~ portional to the input, is fed back to the integrator input

through R8 and Q4. Since the charge balance current-is

much larger than the sum of the input and level shift-currents, the integrator output now ramps in the negative direction until 0 of LJ8B eoes low. The VJA then counts the total numb& of oul& that occur during the charze

balance phase. *

Range

3oomv 3-300V

All

3k-E&*

All All

;ain ==I

At the end of the charge balance phase, the output of the integrator is resting at some positive voltage. Since the in-

tegrator output is connected to the non-inverting~ input of the final-slope comparator (U5B), the final-slope cornpar&o+ output remains high until the integrator output

ramps in the negative direction. During fin@-slope, Q4 is

huned off and the feedback is fed through U16 back to the integrator input;The fmal-slope comparator output is then gated with the 3.84MH.z clock and counted. Once the comparator output goes low, the VJA stops counting and the reading can be computed.

5-7

PRINCIPLES OF OPERATION

., ..,

CURRENT

3.84NHz

CLOCK

U43D

> IO 1102

lJ88

-0

-ii

FINAL SLOPE

COMPARATOR

RllF

DUTY CYCLE COMPARATOR

U7.

us4

FEEDBACK

CONTROL CIRCUIT

Figure 5-6. AID Converter Simplified Schematic

5.5 CONTROL CIRCUITRY

The signals for the circuitry that provides control of the

”

arious FETs, relays, analog switches and logic levels are supplied by the shift store registers U.29, U30, U31, and U32 (see schematic 196-126, page 3). CLOCK, DATA and !ZROBE signals are sent from the VIA (U109) across the pulse transformers T103, T104 and TlO5 (see ~schematic 196-106). The pulse transformers provide 5OOV isolation be-

tween the analog and dig&J sqtions of~tlw~nstrument. DKIYA is serially loaded into the shift store registers and a

STROBE pulse causes the registers to simultaneously~~ut-

put the appropriate logic levels to the FET, analog switch and relay drivers.

5-8

5.6 DIGITAL CIRCUITRY

The Model 196 is controlled by an internal microcomputer.

This section briefly desoibes the operation of the

microcomputer and associated digital circuitry. Refer to schematic diagram number 196-106 ftir circuit details.

5.6.1 Microcomputer

The microcomputer centers around the 8-bit 68809 microprocessor. The MPU has direct control over the display, front panel switches, AID converter, IEEE488 bus,

PRINCIPLES OF OPERATION

as welI as the VOLTMETER COMPLETE Output and the FXTERNAL TRIGGER Input. Timing for the microprocessor is accomplished by the use of X01; an SMH!z crystal. Internally, this frequency is divided~ down by four to obtain a bus operating frequency ofZMHz.

Instrument operation software is stored in EPROMs U105 and U106. The revision level of this software is displayed by Program 0 (Menu). Calibration constants, Translator words and instrument set up conditions ati ~stti*d in E*I’ROM (UlO8). Ul!l7 is the RAM. Partial address decoding is use~d in this system. The function selected is d&en-n% ed by the state of All, Al2, Al?, Al4 and Al5 address lines. These address lines determine which is selected by the decoders (U101). Only one device WOM, RAM, VIA, etc) will have access to the data bus at any one time.

The heart of the IEEE-488 circuiixy is the GPIBA (Ull2). The GPIBA is capable of performing aII IEEE talker-listener protocols. The bidirectional data lies DON through D7 permit the transfer of data between the microprocessor and the GPISA. The transceivers Ull3 and Ull4 are used to drive the output. Data is buffered by Ull3 and U114 and iS transmitted to the bus via connector Jl5.

5.6.2 Display Circuitry

The display information is sent through display latches UllO

and Ulll. Upon each display update, new segment~information is presented to the display latches and a clock pulse is sent on l”. The clock pulse to U4 and U5 (see schematic

196-116) shifts a digit enable bit to the next digit to be enabled. Every 10 times the display is updated, a digit enable it is generated at PA1 and goes to the data input of the shift register. Ul28 through Ul.31 are the drivers for the LED segments of the display digits tid the LED indicators.

5.7 POWER SUPPLIES

The main power supplies of the Model 196 are located on

sheet 1 of 2 of schematic drawing number 196-106. Fuse FlOl is the line fuse which is accessible from the rear panel. 5102 is the POWER ON/OFF switch and SlOl selects ll5V or 230V operation by placing the transformer primary windings in parallel or series. The power transformer, TlOl, has three secondary windings; one for the +5V digital supply, one for the +5V analog supply and one for the kl5V analog supply. CRlOl, CR102 and CR103 provide fullwave rectifica-

tion for the three supplies, while VRlOl through VR104 provide the regulation.

5-9/5-10

SECTION 6

MAINTENANCE

6.1 INTRODUCTION

This section contains information necessary to maintain, calibrate, and troubleshoot the Model 196. Fuse replacement and line voltage selection procedures are also included.

WARNING

The procedures included in this section are for

use onlv bv aualiffed service oersonnel. Do not perform the& procedures unless qualified to do so. Many of the steps in this section may expose you to potentially lethal voltages that could result in personal injury or death if normal safety precautions are not observed.

6.2 LINE VOLTAGE SELECTION

The Model 196 may be operated from either lll5-l25V or 210~25OV 50 or 6OHz power sources. The instrument was shipped from the factory set for an operating voltage marked on the rear panel. To change the line voltage, proceed as follows:

Table 6-1. Line Voltage Selection

Line

Voltage

105v-lzv 5OHz--6OHz lO5v-lz5v

21Ov-25Ov

Line

Frequency Setting

50Hz-6OHz 21ov-25Ov

Switch

6.3 FUSE REPLACEMENT

The Model 196 has two fuses for protection in case of

overload. The line fuse protects the line power input of the

instrument and the current fuse protects the current func-

tion from excessive current. The fuses may be replaced by using the procedures found in the following paragraphs.

WARNING Disconnect the instrument fmm the power line and from other equipment before replacing

fuses.

6.3.1 Line Fuse

WARNING Disconnect the line cord and all other equipment from the Model 196.

1. Place the line voltage switch, located on the rear panel, in the desired position. See Table 6-l for the correct position.

2. Install a power line fuse consistent with the line voltage. See paragraph 6.3.1 for the fuse replacement procedure.

CAUTION The correct fuse type must be used to maintaln proper instrument protection.

3. Mark the selected line voltage on the rear panel for future reference (to avoid confusion, erase the old mark).

To replace the line fuse, proceed as follows:

1. Turn off the power and disconnect the line cord and all other test cables from the instrument.

2. Place the end of a flat-blade screwdriver into the slot in

the line fuse holder on the rear panel. Push in and rotate the fuse carrier onequarter turn counterclockwise. Release pressure on the holder and its internal spring will push the fuse and the carrier out of the holder.

3. Remove the fuse and replace it with the proper type using Table 6-2 as a guide.

CAUTION Do not use a fuse with a rating higher than specified or instrument damage may occur. If the instrument repeatedly blows fuses, locate and correct the cause of the trouble before replacfng the fuse.

4. Install the new fuse and the carrier into the holder by reversing the above procedure.

6-l

MAINTENANCE

Table 6-2. Line Fuse Replacement

I Line I I Keithlev

Voltage 1 Fuse %e

9OV-125V 1/4A, 25OV, Slo-Blo, 3AG

18OV-250V 1 /SA. 250V. Slo-Blo. 3AG m-20

6.3.2 Current Fuse

The current fuse protects the 3CQA through 3A ranges from an input current greater than 3A. To replace the current

fuse, perform the following steps:

1. Tuin off the power and disconnect the power line and test leads.

2. Place the end of a flat-blade screwdriver into the slot in

the fuse holder on the rear panel. Press in slightly and

rotate the fuse carrier onequarter turn counterclockwise. (Program 36) or over the IEEE-488 bus. Release pressure and remove the fuse carrier and the fuse.

3. Remove the defective fuse and replace it~using Table 6-3 as a guide.

CAUTION Use only the recommended fuse type. If a fuse with s higher current rating is installed, instrument damage may occur.

~~~~~ I p=cY6

Fu-I7

6.4 CALIBRATION

Calibration should be performed every 12 months, or if the

performance verification procedures in Section 4 show that the Model 196 is out of specification. If any of the calibration procedures in this section cannot be performed properly, refer to the troubleshooting information in this section. If the problem persists, contact your Keithley represen-

tative or the factory for further informatxon.

NOTE

Check that the instrument is set to the proper line

frequency before proceeding with calibration.

~~ entjre &brafion procedure may be performed without having to make any internal adjustments if high frequency

(701612) has been verified, as explained in paragraph 6.4.10,

step 5. Calibration can be performed from the front panel

NOTE

A ~“CONFLICT” error will be displayed, and the CONFLfCT error bit in <he Ul status word will be set when trying to calibrate the instrument while it is in an improper state (i.e. dB). Also, ifan

“UNCAK’ error occurs, be sure to check the line

frequency setting before performing calibration.

4. To replace the fuse carrier with the fuse, reverse the procedure in step 2.

Table 6-3. Current Fuse Replacement

Fuse Type

3A, 25OV, 3AG,~Normal-Blo / Fu-82

Fluke Fluke

/ Keithley Part No.

Table 6-4. Recommended Calibration Equipment

Description

DC Voltage Calibrator -’ AC Voltage Calibrator

AC Power Amplifier

Current Calibrator

6.4.1 Recommended Calibration Equipment

Table 6-4 lists recommended calibration equipment. Alternate equipment may be used as long as eqGp&ent accurxy is at least as good as the specifications listed in the table.

.,. ,~ ,~ ~, ._I~~

Specification9

3Oomv, 3v, 3w, 3oov ranges *l5ppm 3oomv, 3v, 3ov ranges; 20% *0.10/o;

50&-2Old-h 0.02%; lO4lkHz -10.33% 300V range; 2OHz fO.l2%; 5OH.z-2OkHz

*0.049/o; lookHz fO.l%

3OOiL3MO ranges; fl5ppm; 30MQ

k32ppm; 3OOMfi +225ppm

3OOfi-3A ranges *0.025%

~,,

6-2

6.4.2 Environmental Conditions

Calibration should be performed under laboratory conditions having an ambient temperature of 23°C +YC and a relative humidity of less than 70%.

6.4.3 Warm-Up Period

Turn on the instrument power and allow it to warm up for at least two hours before beginning the calibration procedure. If the instrument has been subjected to extremes of ttimperahue or humidity, allow at least one additional hour for the instrument to stabilize before beginning the calibration procedure.

6.4.4 CAL ENABLE Switch

A switch, accessible from the front panel, disables or enables front panel and IEEE-488 bus calibration. When the

switch is in the DISABLE position, calibration cannot be performed. The following message will be briefly displayed when attempting to enter the caliiration program while the switch is disabled:

CAL LOCKED

B. Enter Program 36 by pressing the 3 and 6 buttons.

The following message will be displayed briefly:

CAL=

C. The defaukcalibration point, which is a high end

reading for the selected range and function, will now be displayed. Pororpxample, if the 3V DC range was selected in step 2, the following calibration point will be displayed:

3.oooow VW

4. If a different calibration point is to be used, enter the new value using the data buttons (0 through 9). Each press of a data button displays the number at the cursor location (identified by the bright flashing digit), and moves the -or to the n&digit. Jf the cursor is moved past the least significant-digit, it-will move back to the most~sigtiicant digit.

5. Comieti the calibration signal to the instrument.

6. Preis the ENTER button. The following message will be displayed for several seconds:

WORKING

Z The low end calibration point will now be displayed.

For the 3VDC range, the following calibration point will be displayed:

Calibration can only be accomplished with the calibration switch in the ENABLE position.

The switch operates in the same manner as the power switch and is accessed from the front panel with a small bladed screwdriver. In the “out” positioti, klibration is

disabled and in the “in” position, calibration is enabled.

6.4.5 Front Panel Calibration

The following information provides the basic procedure for calibrating the instrument from the fro&panel. A detailed calibration procedure is located in paragraph 6.4.7.

1. Place the calibration switch to the ENABLE position to enable calibration. The switch is accessed from the front panel of the instrument.

2. Select the function and range to be calibrated (DCV, Am, 61, DC4 or ACA).

3. Select the front panel calibration program as follows: A. lkss the PRGM button. The following message will

be displayed:

PROGRAM ?

0.000000 VDC

Note: Calibration can be aborted with either the first or second calibration point~prompt displayed by pressing the PRGM button. The instrument will leave the calibration program without changing the previous calibration constants.

8. If a calibration point other than the one displayed is toes be used, then change the display to the desired value as explained in step 4.

9. Set the level of the caliiration signal to agree with the displayed calibration point;~

10. Press the ENTER button. The following message will be displayed for several seconds:

WORKING

11. The two calibration points will be stored in EYROM and the instrument will now exit the &i&ration program. Select the next range and fundion to be calibrated and repeat steps 3 through 10.

NOTEz If the calibration sources has a~ offset; Set the calibration points to agree with the actual output of the source. For example, if the source has a l$I DC offset on the 300mV DC range, set the calibration points for 3CO.OOlOmV and 000.0010mV.

6-3

6.4.6 IEEE-468 Bus Calibration

IEEE-488 bus calibration is performed in a manner similar to front panel calibration, except that calibration constants are transmitted over the bus instead of being entered from the front panel. By combining appropriate IEEE-488 compatible caliiation equipment with a suitable test program, calibration of the Model 196 could be performed on an automated basis. Refer to Section 3 for complete information on using the IEEE-488 bus. The following information provides the basic procedure for calibrating the ins-ent over the IEEE-488 bus. The detailed calibration procedure starts with paragraph 68.7.

Use the following basic procedure when calibrating the Model 196 over the IEEE488 bus:

1. Place the csliiration switch to the ENABLE position. The switch is accessed from the front panel of the Model 196.

2. Program the desired range and function over the bus. For example, to select the 3OOV DC range, send FOR4X.~

3. The high end of the range is calibrated first. Apply a full range (or near full range) calibration signal to the input of the instnnnent. For example, for the 3oOV DC range, apply 3OOV DC to the instrument.

4. Send the required calibration value preceded by the V command letter and followed by the CO calibration command. For example to calibrate the 3OOV DC range at the

300V calibration point, send V3OOXCOX.

NOTE: Calibration can be aborted at this time by sending an SDC or DCL comman d over the bti.~TheC&bra-

tion constant sent in step 4 will not be stored in E’PROM.

~~~~

HP-85 Progr amming Example-The following simple program demonstrates how to calibrate the Model I.96 over the

bus. The program assumes that the instruments primary

address is ate Z

PROGRAM COMMENTS

10 REMIX&7~07

20FOR I=OTOi

30 MSF ’ ’ RPPLY CAL1

BRkTION SIGML 9

46DISF”ENTERCALI

ERATIDN

COMMAND3 ’

50 INPUT A9

Send remote enable. Set program for one loop. Prompts for calibration signal. Prompt for command.

Input command string from keyboard.

60OUTPUT707;A$

Send command string to

7.96.

70ENTER70iiBB

SODISPB5

90 NEXT~I

Get a reading. Display reading.

Loop back one time.

100 EMD

‘lb run the program, press the HP-85 RUN key. At~the first

set of prompts, apply a fuJl range (or near full range) caliiration signal to the instrument, type in the corresponding calibration co

mmand and press the return key. The computer CRT will then display the calibration value. At the second set of prompts, apply a zero (or near zero) caliirtion signal tc-~the~ inshu~~nt, type in the corresponding calibration command and press the return key. The computer will display the calibration value and store both calibration constants into EY’ROM.

5. The low end of the range is calibrated next, Apply a zero (or near zero) csliiration signal to the input of the in-

strument; For example, for the 3OOV DC range apply OV to the instrument.

6. Send the appropriate calibration

cornman

ds for the second calibration point. For example, to calibrate the zero calibration point of the 3OOV DC range send VOXUX. Note that Cl is used for the second calibration point.

7. Storage of the two calibration points into E%‘RqM automatically occurs when the second calibration command is sent.

8. Repeat steps 1-7 for the remaining ranges and functions.

6-4

6.4.7 Calibration Sequence

C&irate the Model 196 in the order presented in the following paragraphs. The basic sequence is:

1. DC Volts calibration

2. Ohms calibration

3. AC Volts calibration

4. DC Current calibration

5. AC Corrent~calibration

6.4.8 DC Volts Calibration

To calibrate the DCV function, proceed as follows:

NOTE

For front panelcalibration,omitstep 4 of the following procedure. For IEH3-488 bus calibration, omit step 3.

l.Select the DCV function and the 3OOmV range.

2. Connect the DC calibrator to the instrument as shown in Figure 6-l.

NOTE NOTE

Low level measurement techniques should be used Low level measurement techniques should be used when calibrating the 3OOmV DC range. Refer to- when calibrating the 3OOmV DC range. Refer toparagraph 2.6.5 for low level measurement con- paragraph 2.6.5 for low level measurement considerations. siderations.

3. For front panel calibration, select Program 36 and proceed as follows:

A. With the 3OO.OOOOmV DC calibration point displayed

on the Model 196, set the DC calibrator to output

+0.30000oov.

B. After allowing sufficient time for the calibrator voltage

to settle, press the ENTER button. The following message will be displayed for several seconds:

E. The instrument will exit the calibration progrsm and

return to the 3OOmWC range.

E Repeat the procedures in step~3 for the remaining DCV

ranges using Table 6-5 as a guide.

4. For IEEE488 bus calibration, proceed as follows: A.Set the DC voltage calibrator to output +030000OOV. B. After allowing sufficient time for the caliirator voltage

to settle, send the following commands over the bus:

V300E-3XCOX. C. Set the DC voltage calibrator to outputs O.OOOOOOOV. D. After allowing sufficient time for the calibrator voltage

to~settle, send the following comman VOXClX. Both calibration constants will be automatically stored in EzPROM.

E. Repeat steps A through D for the remaining DCV

ranges using Table 6-5 as a guide.

Figure 6-1. DC Volts Calibration Configuration

(300mV and 3V Ranges)

d over the bus:

WORKING

C. With the OONlOOOmV DC calibration poinf displayed,

set the DC caliiator to output O.OOOOOOOV.

D. After allowing sufficient time-for the caliirator voltage

to settle, press the ENTER button. The following message will be displayed for several seconds:

WORKING

Table 6-5. DC Volts Calibration

Set-Up

Figure 6-l

Figure 6-l Figure 6-2 Figure 6-2

Figure 6-2. DC Volts Calibration Configuration

(3OW3OOV Ranges)

IEEE&8

Bus Command

VJBOE-3XCOX

voxclx v3xcox voxclx

V3OXCOX

voxclx

Keithley 196 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual