Keithley 1944A, 1941, 194A User Manual

USING THIS GUIDE

This reference and programming guide contains condensed specifications, a summary of front panel operating controls.

and IEEE-488 programming commands and examples for the Models 194A. 1941, and 1944A. It is intended to provide a quick reference to the many available features of your

instrument as well as the many programming commands

available to control the instrument over the IEEE-488 bus.

Because of the limited amount space available in this guide.

many details abourinstrument operation will not be found here. Refer to the Model 194A Instwction Manual for

aspects of instrument operation not covered in this guide.

This guide describes the following aspects of the Model

194A:

l Front panel operation including XY mode. l A description of mathematical functions.

* Input and output signal connections.

l IEEE-488 programming information, including commands,

data and status formats. and exampkprograms for typical COntrOllers.

01989, Keithley Instruments. Inc.

28775 Aurora Road

Cleveland, Ohio 44139

Document Number: 194A-900-01 Rev. A

CONTENTS

CONDENSED SPECIFICATIONS .~. . . 4 ENGlNEERlNG “NITS CONVERSION . .~. .~.~. ~.._5

SAFElYPRECAUTIONS...................... 6

FRONT PANEL FEATURES AND OPERATlON.. . 7

Display Annunciators Genera, Display Messages Shift Functions Mathematical Functions Ratio and Difference Modes Range Data Entry Programmable Parameters Rate and Samples Programming Recalling Data Trigger Channel Selection Input Coupling Zero Filter

FRONT PANEL PROGRAMS., _~_ _~_ 25

SetUPstatus Reset XY Mode

INPUT AND OUTPUT CONNECTIONS . 3,

A/D Module InpuffOutput Connections Analog Output Connections Enernal Clock

IEEE-466 PROGRAMMING. _, 36

Device-dependent Commands TRANSLATOR MODE.. _. _ .~__ _ _~~ 56 CONTROLLER PROGRAMS t t __ _ __ 56

IBM XT or PC (with CEC Interface1

Hewlett-Pock& 300 Series Compac ASCII CHARACTER CODES AND IEEE-466 MULTILINE INTERFACE COMMAND MESSAGES 62

CONDENSED SPECIFICATIONS

INPUT IMPEDANCE: 1MO in parallel with less than 47pF. MAXIMUM ALLOWABLE INPUT: 260” peak, 2 x 10’” Hz. MAXIMUM SAMPLING RATE: lMHz et 6.bit resolution;

100kHz et 16.bit resolution.

MATH FUNCTIONS: Average, Peak, Peak-to-Peak, TRMS,

Standard Deviation, Integral, Waveform.

FRONT PANEL PROGRAMS: IEEE-466 Address, Self Test,

Digital Calibration, Calibration Storage, X Output Full Scale, Y Output Full Scale, Z Output Blanking Level,

DISPLAY Fourteen digit alphanumeric LED display. RANGING: Manual or autoranging. CONNECTORS: All I/O connectors are BNC except Real

Trme Output IDS-261 and IEEE-466 connectors.

ENGINEERING UNITS AND SCIENTIFIC NOTATION CONVERSION

Prefix

pico“anOmicromilli-

kilomegagigaterapeta-

Engineering

Symbol

Scientific Notation

SAFETY PRECAUTIONS

The following safety precautions should be observed before using the Model 194A:

1. Before operation. ground the instrument through-a properly earth grounded power receptacle

2. Do not exceed 30” rms between input low and earth ground.

3. Do not exceed the maximum allowable input 8s defined in the condensed specifications section of this guide

4. Before servicing. disconnect the Model lg4A from the

power line and all other equipment.

5. Do not touch any terminals while the instrument is turn-

ed on or connected to any other equipment or sources.

FRONT PANEL FEATURES

AND OPERATION

DISPLAY

DESCRIPTION

The Model lg4A display consists of fourteen 14.segment LED units which display both instrument readings as well as many messages to augment the variow operational modes. The basic display format for readings includes the voltage value, units ImV or VI. mathematical function (for example AVG for average) and channel number (1 or 2). Channel 2 is available only for those units equipped with a Model lg44A AID module in the CARD 2 location.

The display can be operated singlechannel or dualchannel, as selected with the CHANNEL button. The selected thannel also dictates which channel is affected by pressing other buttons. Most other modes cannot be changed when the display is in the dual-channel mode

DISPLAY EXAMPLES

Typical examples for the display modes include:

Channel 1 Average Reading: -1.2500 V AVG 1. Channel 2 TRMS Reading: 0.3450 mV RMS 2. Dual Channel Reading: -1.2500 0.3450

ANNUNCIATORS

Front panel annunciators indicate when a number of front panel modes are selected as described below:

IEEE-488 STATUS: The TALK, LISTEN, and REMOTE indicators show when the instrument has been placed in those respective modes via programming commands sent wer the IEEE-488 bus. These indicators are not operational during front panel operation.

ZERO: Indicates when a baseline measurement is being subtracted from subsequent measurements.

FILTER: Shows when either the 5OkHz or 5OOkHr analog

filters are enabled.

SGUCONT: Indicates when the instrument is in the single or ccmtinuou* trigger.

SLOPE: Shows whether the instrument will be triggered on the rising or falling edge of an input signal waveform.

‘CPLG: Indicates BC or dc input coupling. Ground coupling

is selected when both indicators are off.

AUTO: Shows when the instrument is in the autorange

mode.

SHW Shows when the shift mode has been enabled by pressing the shift key. Shifted modes are marked below the respective control buttons.

RECALL: Indicates when the recall mode is in effect. This mode allows access to individual samples in the measurement buffer.

GENERAL DISPLAY MESSAGES

Display messages that may occur during general front panel cpererlcn are summarimzi below. The unit also has a number

of specific messages associated with the various operating

modes, as described in the instruction manual.

MESSAGE DESCRIPTION

OFLO

SHIFTLESS KEY

NMSR TOO SMALL

iwmi7 mo LARGE

Overrange input applied for at least one sample.

Shift function invoked for key not having one.

Too small a value keyed in during data entry.

Too big a value keyed in during data entry.

SHIFT FUNCTIONS

DESCRIPTION

Many of the front panel keys have a secondary function which is placed intoaffect by pressing theSHIFT key before pressing that particular button. Each shifted function is listed below the key in question. For example, pressing SHIFT ZERO VAL allows a baseline value to be keyed in from

the front panel. While the shift function is enabled. the

associated indicator will be on. Pressing a key which does not have a~shifted function will result in the following display message:

SHIFTLESS KEY

MATHEMATICAL FUNCTIONS

DESCRIPTION

The Model 1g4A has a number of mathematical functions that can be applied to the measurement. If the instrument

is in a continuous trigger mode. a single math function, Once selected, can be applied to successive measurements. In a single trigger mode, a variety of different math functions can be applied to a single measurement. Each mathematical function can be enabled by pressing SHIFT followed by the corresponding key.

OPERATION

WAVEFORM: Displays the individual sample occurring at the trigger point, or thesample as close as possible to the trigger point. Example: 1.2345 V DC 1.

PK TO PK: Displays the peak--to-peak value of the measurement, which is calculated by subtracting the most negative

sample from the most positive samples

Eample: 2.3410 V P-P 1.

STD DEW Displays the standard deviation of the measurement, which shows how far the samples deviate from the average of the measurement. Example: -12.341 V STD 1.

INTEGRAL Displays the integral of the measurement, which

is the area under a curve bounded by the measurement amplitude and the measurement duration. Example: 800.23 VS 2.

AVG: Shows the average of the measurement, which is calculated by dividing the sum of all the samples ~bv the number of sample. Example: -16.225 V AVG 1.

TRMS: Displays the true rms value of the meas~rment. Ex-

ample: 31.800 V RMS 1.

PEAK: Shows the most positive or mrxt negative sample

in the measurement. Example: 1.1220 V PK+ 1. Press

repeatedly to alternate between positive and negative peak.

RATIO AND DIFFERENCE MODES

(

0 0~0

00000

DESCRIPTION

The ratio and difference modes allow you to divide the chatnel 1 reading by the channel 2 reading or to subtract the channel 2 reading fmm the channel 1 reading. In order to use either of these modes, the optional Model 1944A A/D Module must be installed in the CARD 2 location. If there is no second channel installed, pressing either CHl-CHZ or CHl+CHZ module installed will result in the following message:

NOAiDINCH2

OPERATION

CHlrCH2 IRatio): To display the ratio between the two channels, press SHIFT CHltCH2. The instrument will then display the ratio as in this example: 1.2367 V l/2.

CHI-CH2 (Differencel: To display the difference between the two channekpress SHIFT CHl-CHZ. The instrument will then display the difference between the two channels. as in this examole: 2.4000 V 1-2.

RANGE

DESCRIPTION

The ranging controls give you control over sensitivity of the

measurement The range may be selected either on an automatic or manual basis. When using manual ranging, the lowest rangepossible without overranging the instru-

ment should be used to maximize accuracy and resolution.

OPERATION

AUTO: The AUTO button toggles the instrument between

auto and manual ranging. The AUTO indicator will be on when in autoranging.

Uprange: Pressing uprange moves the instrument to the next higher range until the highest (2OOVl range is reached, Uprange also cancels autorange if that mode is presently

enabled. Uprange is also used with various other functions such as data entry and recall.

Downrange: This key moves the instrument to the next lower range when pressed until the lowest I32OmVl range is reached. Downrange also cancels autorange if enabled. and it is used with various other functions such as data entry and recall.

The Data Entry keys allow the entry of numeric data into those functions requiring values. These keys are used to program values for rate. samples, trigger kvel. zero, and trig get delay. During the entry process, the keyed in digits will

appear on the display.

OPERATION

Numeric Keys (O-9. +/-,. I: These keys enter actual numeric data including decimal point and sign into the display after the appropriate function has been entered.

ENTER: Pressing ENTER actually enters keyed in data into the function in question.

CANCEL: May be used to cancel keyed in data and return to the previous value.

Units Keys (MHz, kHz, Hzl: Determines the type of units to be keyed in. Voltage or time or frequency units are automatically chosen by the selected function. Pressing a units key automatically enters the displayed data.

FRED/TIME: This key toggles the instrument between time

t@ec, msec, sl and frequency (MHz, kHz, Hz1 units. For example, sampling rate may be entered either as time interval or sampling frequency units.

Cursor Control: During the data entry process. the digit affected by pressing a numeric keey will be indicated by a flashing segment or digit. This cursor can be moved left or right with the downrange or uprange buttons. respectively.

PROGRAMMABLE PARAMETERS

Perameten to be programmed with the Date Entry keys are summarized below, along with limits and resolution of each parameter.

FUllCtkJ~

Limits

bsohJtion

RATE

SAMPLES

DELAY

LEVEL ZERO “AL x output Full Scale*’ Y Output*~ Full Scale

Time Irsec-lsec Frequency lHz-1MHz No: l-65.535* lime: Opsec-65,534sec’ NO Samples: -65,536 to

10’

‘lime: -65,536 to 10’sec

*20CW *2ocw

l-1OV nominal

RATE AND SAMPLES PROGRAMMING

0.1 rrjec HZ

Samples

0.1 *ec

Samples

DESCRIPTION

A measurement is made up of a number of samples taken at specific intervals. The number of samples in that measurement, as well as how fast those samples are taken

can be programmed with the SAMPLES and RATE keys. These parameters are entered with the Data Entry keeys O~CB the mode in question is enabled.

RATE: Sampling rate may be entered in time (Isec -lpecl or frequency (IHI-1MHr). To program sampling rate, press the RATE key and press the numeric buttons in the desired sequence. Press the FRECUTIME key, as required, to enter

time or frequency units.

SAMPLES: The size of the measurement may be entered

as the number of samples 11-65.536) or measurement time

duration il#ec-65,536secl. To program the number of

samples, press SAMPLES and then key in the desired value

withy the numeric keys. Use FREQiTlME to select sampling

interval or number of samples, as desired.

RECALLING DATA

DESCRIPTION

Recall allcw you tc display individual samples within the measurement. This mode is entered by using the RECALL button. Once in the recall mode, individual samples may be accessed on a sequenr,al or random basics.

OPERATION

To enter recall, simply press the RECALL button. While in this mode, the RECALL indicator button will be on. To access individual samples, either use the uprange or downrange keys to access individual samples, or key in a specific sample number and press the ENTER key.

TRIGGER

DESCRIPTION

The Model 194A may be triggered in a variety of different ways: with the TRIGGER button. with an input ~pulse ap- plied to the TRIGGER IN jack, from the other channel, or from the input signal. When triggering from the input signal, the slope and trigger level can be programmed.

OPERATION

SOURCE: To select the trigger scum?, press SOURCE repeatedly until the desired mode is displayed: front panel (TRIGGER), input signal, external. or other channel. Press

CHANNEL to save the selected source.

SGUCONI A measurement sequence can beperformed on

a continuous or single basis. In a continuous mode, the in-

strument repeatedly arms the A/D for the next trigger

measurement without requiring additional triggers. In the

single mode, B separate arm stimulus is required for each

measurement. SGLICONT toggles the instrument between

these two modes, as indicated by the respectiwindicator.

TRIGGER: When selected with the SOURCE key,pressing

this keey will initiate a continuous or single measurement,

depending on the selected mode

SLOPE: Rising or falling edge triggering may be selected with the SLOPE key only when input signal triggering is selected. The annunciator next to the key indicates the selected mode

LEVEL: When triggering from the input signal, the actual voltage level et which the unit is triggered may be selected with the LEVEL key. Once this mode is entered, the voltage is keyed in with the Data Entry keys.

DELAY Delay selects the number of samples between the trigger and the first sample A positive or negative delay

may be selected. Delay may be entered in number of samples or actual time by using the FREOrrlME key.

+ 44 hidden pages