Agilent 34420A Users Guide

User’s Guide

Part Number 34420-90001 December 1994

For Safety information, Warranties, and Regulatory information, see the pages behind the Index.

HP 34420A Nano Volt/Micro Ohm Meter

The HP 34420A is a 7 meter. Its combination of bench-top and system features makes this meter a versatile solution for your testing requirements now and in the future.

Convenient bench-top features

• Built-in math operations including thermistor, thermocouple and

RTD temperature measurements

• Two channel input allows ratio and difference functions for voltage

measurements

• Highly visible vacuum-fluorescent display

• Portable, ruggedized case with non-skid feet

Flexible system features

• HP-IB (IEEE-488) interface and RS-232 interface are standard

• SCPI (Standard Commands for Programmable Instruments) and

Keithley 181 compatibility

• Readings at up to 250 per second

digit, high performance nanovolt, micro-ohm

HP 34420A Nano Volt/Micro Ohm Meter

The Front-Panel at a Glance

1 Input channel select 5 Menu operation keys 2 Measurement function keys 6 Range/number of dig its displayed keys 3 Math operation key s 7 Single trigger/autot r ig ger/a ut o hol d key 4 Filter select key 8 Shift / local key

The Front-Panel Menu at a Glance

The menu is organized in a top-down tree structure with three levels.

To turn on menu press:

To enter a command press:

To move left/right To move up/down

A: MEASurement MENU

1: DIG FILTER Ø 2: INTEGRATE Ø 3: OCOMP Ω Ø 4: LOW POWER Ω Ø 5: LOW VOLT Ω Ø 6: LoV LIMIT Ω

B: TEMPerature MENU

1: PROBE TYPE Ø 2: UNITS Ø 3: RTD TYPE Ø 4:RTD Ro Ø 5: T/C TYPE Ø 6: COLD JUNCT Ø 7: JUNCT TEMP

C: MATH MENU

1: STATS Ø 2: NULL VALUE Ø 3: SCALE GAIN Ø 4: SCALE OFST

D: TRIGger MENU

1: READ HOLD Ø 2: TRIG DELAY Ø 3: N SAMPLES

E: SYStem MENU

1: RDGS STORE Ø 2: SAVED RDGS Ø 3: ERROR Ø 4: TEST Ø 5: CHART OUT Ø 6: CHART SPAN 7: CHART NULL Ø 8: DISPLAY Ø 9: COMMA Ø 10: PRESET Ø 11: REVISION

F: Input/Output MENU

1: HP-IB ADDR Ø 2: INTERFACE Ø 3: BAUD RATE Ø 4: PARITY Ø 5: LANGUAGE

G: CALibration MENU

1: UNSECURED Ø [1: SECURED] Ø [2: CALIBRATE] Ø [3: CHART ZERO] Ø [4: CHART GAIN] [5: INJECTED I] Ø 6: CAL COUNT Ø 7: MESSAGE

NOTE: The commands enclosed in square brackets ([ ]) in the CAL MENU a re "hidden" unless th e meter is UNSECURE D for calibration.

Display Annunciators

Adrs Meter is addressed to listen or talk over the HP-IB interface. Rmt Meter is in remote mode (using remote interface). Man Meter is using manual ranging (autorange is disabled). Trig Meter is waiting for a single trigger or external trigger. OC Off Offset compensation is turned off. Null A null value is being used. Stats Math statistics operations are being used. Scale Math scaling operations are being used. ERROR Hardware or remote interface command error(s) detected. Shift "Shift" key has been pressed. Ch1 Meter input is on Channel 1. Ch2 Meter input is on Channel 2. Ch1 - Ch2 Meter is indicati ng the difference between inputs on channel 1 and channe l 2. Ch1 / Ch2 Meter is indicating the ratio of the inputs on channel 1 and channel 2.

Ω Meter is measuring resistance (Ohms).

LP Meter is using low power Ohms. 2W Meter is using 2-wire Ohms (annunciator off indicates a 4-wire measurement). LoV Meter is using voltage li mited Ohms. Hold Automatic reading hold is enabled. Filt The analog and/or the digital filter is enabled. Mem Turns on when reading memory is enabled.

Turns on during a measurement.

To review the display annunciators, hold down the Shift key as you turn on the meter.

The Rear Panel at a Glance

1 Chassis ground 5 Voltmeter complete output terminal 2 Power-line fuse-holder assembly 6 External trigger input te rminal 3 Power-line voltage setting 7 HP-IB (IEEE-488) interface connector 4 Chart recorder out pu t ter minal

(Analog out)

8 RS-232 interface connector

Use the front-panel Input / Out put Menu to :

• Select the HP-IB or RS- 232 int er fa ce

• Set the HP-IB bus address

• Set the RS-232 baud rate and parity

In This Book

Quick Start Chapter 1 prepares the meter for use and helps you get familiar with a few of its front-panel features.

Front-Panel Operation Chapter 2 introduces you to the front-panel menu

and describes some of the meter’s menu features.

Features and Functions Chapter 3 gives a detailed description of the meter’s capabilities and operation. You will find this chapter useful whether you are operating the meter from the front panel or from a remote interface.

Remote Interface Reference Chapter 4 contains reference information to help you program the meter using a remote interface.

Error Messages Chapter 5 lists the error messages that may appear as you are working with the meter. Each listing contains enough information to help you diagnose and solve the problem.

Application Programs Chapter 6 contains several remote interface application programs to help you develop programs for your measurement application.

Measurement Tutorial Chapter 7 discusses measurement considerations and techniques to help you obtain the best accuracy and reduce sources of measurement error.

Specifications Chapter 8 lists the meter’s specifications and describes how to interpret these specifications.

If you have questions relating to the operation of the meter, call

1-800-452-4844 in the United States, or contact your nearest

Hewlett-Packard Sales Office.

Chapter 1 Quick Start

To Prepare the Meter For Use 13 If the Meter Does Not Turn On 14 To Adjust the Carrying Handle 16 To Make Input Connections 17 To Measure Voltage 19 To Measure Resistance 20 To Measure Temperature With Thermistors 21 To Measure Temperature With RTDs 21 To Measure Temperature With Thermocouples 22 To Select a Range 23 To Set the Number of Digits 24 To Set the Integration Time 25 Front-Panel Display Formats 26 To Rack Mount the Meter 27

Chapter 2 Front-Panel Operation

Front-Panel Menu Reference 31 A Front-Panel Menu Tutorial 33 To Select an Input Channel 41 To Select a Range 42 To Set or Change the Number of Digits 43 To Set the Integration Time 44 To Make Null (Relative) Measurements 45 To Store Minimum and Maximum Readings (Stats) 46 To Trigger the Meter 47 To Use Reading Hold 48 To Make Voltage Ratio and Difference Measurements 49 To Use Reading Memory 50

Chapter 3 Features and Functions

General Measurement Configuration 55

Input Filters 55 Integration Time 58 Reducing Measurement Noise 60 Number of Digits Displayed 62 Ranging 64 Overload Detection 65

Voltage Measurement Configuration 66

Input Channels 66 Resistance Measurement Configuration 68 Temperature Measurement Configuration 71

Measurement Units 71

RTD Measurements 72

Thermistor Measurements 72

Thermocouple Measurements 73

o n

t e n

t s

Contents

Chapter 3 Features and Functions (continued)

Math Operations 74 Null (Relative) Operation 77 Reading Hold 79 Triggering 80

Trigger Source Choices 82 The Wait-for-Trigger State 85 Halting a Measurement in Progress 85 Number of Samples 86 Number of Triggers 86 Trigger Delay 87 Automatic Trigger Delays 89

System-Related Operations 90

Reading Memory 90 Error Conditions 92 Self-Test 93 Display Control 94 Comma Separators 95 Firmware Revision Query 95

SCPI Language Version 96 Voltmeter Complete Terminal 97 External Trigger Terminal 97 Chart Output (Analog Output) 98

Chart Rollover 100 Remote Interface Configuration 101

Remote Interface Selection 101

HP-IB Address 102

Baud Rate Selection (

Parity Selection (

Programming Language Selection 105

Connection to a Terminal or Printer (RS-232) 106 Calibration 107

Calibration Security 107

Calibration Count 110

Calibration Message 111 Defaults, Power-On and Reset States 112

RS-232) 103

RS-232) 104

Chapter 4 Remote Interface Reference

Command Summary 117 Simplified Programming Sequence 126

Using the

Using the range and resolution Parameters 129

Using the READ? Command 130

Using the INITiate and FETCh? Commands 131 The MEASure? and CONFigure Commands 134 Setting the Function, Range, and Resolution 137 Selecting the Input Channel 140 Special Resistance Measurement Commands 141 Temperature Measurement Commands 142

MEASure? Command 128 CONFigure Command 128

Contents

Chapter 4 Remote Interface Reference (continued)

Null (Relative) Commands 145 Input Filter Commands 146 Math Operation Commands 148

Statistics operation commands (AVERage) 149 Scale operation commands 150

Triggering 151

The Wait-for-Trigger State 153 Triggering Commands 154 Chart Output (Analog Out) Commands 156 System-Related Commands 157 The SCPI Status Model 159

What is an Event Register? 159

What is an Enable Register? 159

What is a Condition Register? 159

SCPI Status System 160

The Status Byte 161

Using Service Request (

Using

*STB? to Read the Status Byte 163

To Interrupt Your Bus Controller Using

To Determine When a Command Sequence is Completed 163

How to Use the Message Available Bit (MAV) 164

*OPC to Signal When Data is in the Output Buffer 164

Using

The Standard Event Register 165

The Questionable Data Register 167

The Operational Status and Condition Registers 169 Status Reporting Commands 171 Calibration Commands 174 RS-232 Interface Configuration 176

RS-232 Configuration Overview 176

RS-232 Data Frame Format 177

Connection to a Computer or Terminal 177

Connection to a Printer 179

DTR / DSR Handshake Protocol 179

RS-232 Troubleshooting 181 RS-232 Interface Commands 182 An Introduction to the SCPI Language 183

SCPI Data Types 185 Input Message Terminators 186 Output Data Formats 186 Using Device Clear to Halt Measurements 187 TALK ONLY for Printers 187 To Set the HP-IB Address 188 To Select the Remote Interface 189 To Set the Baud Rate 190 To Set the Parity 191 To Select the Programming Language 192 Alternate Programming Language Compatibility 193

Specific Issues 193 SCPI Compliance Information 194 IEEE-488 Compliance Information 197

SRQ) and Serial POLL 162

SRQ 163

o n

t e n

t s

Contents

Chapter 5 Error Messages

Execution Errors 201 Self-Test Errors 208 Calibration Errors 210

Chapter 6 ApplicationPrograms

HP BASIC Language Programs 215

HP BASIC / HP-IB Program Example 1 215 HP BASIC / HP-IB Program Example 2 216 HP BASIC / HP-IB Program Example 3 218

HP BASIC / HP-IB Program Example 4 221 RS-232 Operations with QuickBASIC 223 Microsoft

Visual Basic Language Program 224

C Language Programs 231

Compiling and Linking a C Program 231

C / HP-IB Example 1 233

C / HP-IB Example 2 235

C / HP-IB Program Example 3 239

Microsoft

Excel Macro Example 243

Macro Comments 244

Chapter 7 Measurement Tutorial

Measurement Techniques and Sources of Error 249

Voltage Measurements 249

Resistance Measurements 258

Temperature Measurements 263 Cleaning the Connector Contacts 271 Input Connector 272 Obtaining Parts For the Input Connector 273

Chapter 8 Specifications

Accuracy Specifications Measurement Characteristics Operating Characteristics Dimensions To Calculate Total Measurement Error 281 Interpreting Meter Specifications 285

Number of Digits and Overrange 285

Sensitivity 285

Resolution 286

Accuracy 286

24-Hour Accuracy 287

90-Day and 1-Year Accuracy 287

Temperature Coefficients 287 Configuring for Highest Accuracy Measurements 287

Index 289

Declaration of Conformity 295

Quick Start

This chapter helps you prepare the meter for use and contains exercises designed to get you started with the meter, its menus, and the front panel.

The front panel has two rows of keys to select various functions and operations. Most keys have a shifted function printed in blue above the key. To perform a shifted function, press annunciator will turn on). Then, press the key that has the desired label above it. For example, to select the temperature measurement function,

Shift DCV .

press

Shift (the Shift display

If you accidentally press annunciator.

The rear cover of this book is a fold-out Quick Reference Guide. On this cover you will find a quick summary of various meter features. Inside the rear cover is a diagram of the front panel menu options.

Shift , just press it again to turn off the Shift

Chapter 1 Quick Start

To Prepare the Meter For Use

The following steps help you verify that the meter is ready for use.

1 Check the list of supplied items.

Verify that you have received the following items with your meter. If any item is missing, contact your nearest Hewlett-Packard Sales Office.

One low thermal input cable.

One low thermal four-wire shorting plug.

One power cord.

This User’s Guide.

One Service Guide.

One folded Quick Reference card.

Certificate of Calibration with removeable calibration label.

One bottle of DeoxIT contact cleaner.

2 Connect the power cord and turn the meter on.

The front panel display will light up while the meter performs its power-on self-test. The HP-IB bus address is displayed. The meter is left

digit resolution, channel 1 input, and digital filter on.

in 6

To view the display with all annunciators turned on, hold down

3Perform a complete self-test.

The complete self-test performs a more extensive series of tests than those performed at power-on. Hold down power switch to turn on the meter; continue to hold 5 seconds. The self-test will begin when you release the key.

If the self-test is successful, "PASS" is displayed on the front panel. If the

test is not successful, "FAIL" is displayed and the ERROR annunciator

turns on. See the Service Guide for instructions on returning the meter to Hewlett-Packard for service.

DeoxIT is a trademark of CAIG Laboratories, Inc., San Diego, California.

Shift as you turn on the meter.

Shift as you press the

Shift for more than

Chapter 1 Quick Start

If the Meter Does Not Turn On

Use the following steps to help solve problems you might experience when turning on the meter. If you need more help, see the Service Guide for instructions on returning the meter to Hewlett-Packard for service.

1 Verify there is ac power to the meter.

First verify that the meter’s power switch is in the "On" position. Make sure the power cord is firmly plugged into the power module on the meter’s rear panel. Verify that the power source is energized.

2 Verify the power-line voltage setting.

The line voltage is set to the proper value for your country when the meter is shipped from the factory. Change the voltage setting if it is not correct. The settings are: 100, 120, 220, or 240 Vac (for 230 Vac operation, use the 220 Vac setting).

See the diagram on the next page to verify or change the setting.

To replace the 250 mAT 250 V fuse, order HP part number 2110-0817.

This fuse is used for all power line voltage settings.

Chapter 1 Quick Start

If the Meter Does Not Turn On

1 Remove the power cord. Remove

the fuse holder assembly from the rear

3 Rotate the line-voltage selector until

the correct voltage appears in the window.

2 Install the fuse. Remove the

line-voltage selector from the assembly.

250 mAT fuse (250V)

4 Replace the fuse-holder assembly in the

rear panel.

100, 120, 220 (230), or 240 Vac

Install the correct fuse and verify that the correct line voltage appears in the window.

Chapter 1 Quick Start

To Adjust the Carrying Handle

To adjust the position, grasp the handle by the sides and pull outward. Then, rotate the handle to the desired position.

Bench-top viewing positions

Carrying Position

Chapter 1 Quick Start

To Make Input Connections

Using the Cable Provided

Align the front panel connector and cable conductors, press in. Tighten coupling nut.

Torque to 20 in-lb

maximum

CH1 BLACK LO

CH2 GREEN

RED HI

WHITE

Warning

The connector and cable are an integral part of the measurement system. For the highest accuracy, use the copper cable and connectors supplied by Hewlett-Packard.

The conductors may require occasional cleaning to remove oxides. Cleaning the conductors is described on page 271.

The connector body and cable shield are connected to earth ground.

Chapter 1 Quick Start

To Make Input Connections

Using a Custom Cable

Channel 1

HI LO

DCV + – 4-WireΩ 2-WireΩ

Thermistor Source and Sense + Source and Sense –

Source + Source –

Source and Sense + Source and Sense –

Earth Ground (shell)

Channel 2

HI LO

DCV + –

4-WireΩ

Thermocouple + –

Sense + Sense –

Refer to page 272 for additional information about building custom input cables.

Chapter 1 Quick Start

To Measure Voltage

Channel 1 Ranges: 1 mV, 10 mV, 100 mV, 1 V, 10 V, 100 V

Maximum resolution: 0.1 nV (on 1 mV range)

Channel 2 Ranges: 1 mV, 10 mV, 100 mV, 1 V, 10 V

Maximum resolution: 0.1 nV (on 1 mV range) Independent NULL for each channel Channel 1 LO to Channel 2 LO isolated to 150 Vpeak.

RED

DC Voltage

BLACK

CH1

CH2 GREEN

WHITE

DC Voltage

DIFFERENCE RATIO

VOLTAGE

TOGGLES MEASUREMENT CHANNEL

(SCAN) ALTERNATING MEASUREMENT CHANNELS

Scan mode alternates between input channels every 3 seconds or every measurement, whichever is longer.

Chapter 1 Quick Start

To Measure Resistance

Ranges: 1 Ω , 10 Ω , 100 Ω , 1 kΩ , 10 kΩ , 100 kΩ , 1 MΩ Maximum resolution: 0.1 µ Ω (on 1 ohm range)

See also Resistance Measurements on page 68.

RED

(SOURCE)

CH1 GREEN

CH2

(SENSE) WHITED

4-WIRE

RED

2-WIRE

4-WIRE

BLACK

SOURCE

BLACK

GREEN

NOT CONNECTED

WHITE

Resistance measurements use offset compensation. Offset compensation can be disabled if desired (see page 69).

2-WIRE

Chapter 1 Quick Start

To Measure Temperature With Thermistors

Thermistor type: 5 kΩ

RED

CH1 BLACK

GREEN

WHITE

To Measure Temperature With RTDs

4-wire, type: α = .00385 (DIN/IEC 751) or α = .00391

= 4.9 Ω to 2.1 kΩ

OPEN

RED

(SOURCE) CH1 GREEN

CH2

(SENSE) WHITE

BLACK

Chapter 1 Quick Start

To Measure Temperature With Thermocouples

Thermocouple types: B, E, J, K, N, R, S, T Reference: external thermistor, external fixed value, or internal thermistor.

Channel 2 only.

ISOTHERMAL BLOCK

RED

CH2

INTERNAL

CH1 BLACK THERMISTOR

GREEN

CH2

RED

CH1 OPEN

BLACK

GREEN

CH2

WHITE

FIXED VALUE

ICE BATH

REFERENCE

EXTERNAL

When using the internal thermistor as the temperature reference, you should make a custom cable to connect the thermocouple wire directly to the input terminals (see page 272).

Chapter 1 Quick Start

To Select a Range

You can let the meter automatically select the range using autoranging or you can select a fixed range using manual ranging.

Toggles between autoranging and manual ranging

Selects a higher range and disables autoranging

Selects a lower range and disables autoranging

• Autoranging is selected at power-on and after a remote interface reset.

Man annunciator is on when manual range is enables

• Autorange thresholds:

Down range at <10% of range Up range at >120% of range

• If the input signal is greater than the present range can measure, the

meter will give an overload indication ("OVLD").

• When making difference or ratio measurements, an overload on either

channel will give an overload indication ("OVLD").

For voltage measurements, ranging is local to the selected channel. This means that you can select the ranging method (auto or manual) for each channel independently. When manually ranging, the selected range is local to the active channel; the meter remembers the range when you switch between channels.

Chapter 1 Quick Start

To Set the Number of Digits

You can set the display to show 4

⁄

, 5

⁄

, 6

⁄

book, the most significant digit (leftmost on the display) is referred to as

⁄

the “

” digit, since it can only be a “0” or “1”. The number of digits

displayed also depends upon the integration time set, see page 25.

, or 7

⁄

digits. In this

Press the Shift key

Selects 5 (1 PLC)

⁄2 digits

• The number of digits is set to 6

Selects 7 (100 PLC)

Selects 6 (10 PLC)

⁄2 digits

⁄

digits at power-on and after a

⁄2 digits

remote interface reset.

• The number of digits shown is dependent upon integration time and

filter settings. The meter will not allow you to show more digits than the practical measurement capability of the meter. You can, however, reduce the number of digits shown.

Fewer More Digits Digits

Chapter 1 Quick Start

To Set the Integration Ti me

To Set the Integration Time

Integration time is specified in Number of Power Line Cycles (NPLC). You can set the NPLC to 0.02, 0.2, 1, 2, 10, 20, 100, or 200.

• You can set the integration time to one of three fixed values by

choosing the number of digits displayed, see page 24.

• You can set the integration time in the MEASure menu using the

INTEGRATE command.

• The Integration Time is directly related to the maximum number of

digits the meter will display.

NPLC

0.02

0.2 1 2

20 100 200

Filter Off

Max Digits Shown

41⁄2 5 51⁄2 6 61⁄2 7 61⁄2 7

⁄2 7

6 71⁄2 7 71⁄2 7 71⁄2 7

Filter On

Max Digits Shown

⁄2

• You can always show fewer digits than the maximum allowed

⁄

(the minimum number of digits shown is 4

Integration Time is local to the selected function. This means that you can select the integration time for each function independently. The meter remembers integration time when you switch between functions.

6 digits

Chapter 1 Quick Start

Front-Panel Display Formats

-H.DDD,DDD,D EFF

Front-panel display format.

- Negative sign or blank (positive)

H "1/2" digit (0 or 1) D Numeric Digits E Exponent (m,k,M) F Measurement units

"1/2" digit

5 digits

"1/2" digit

7 digits

"1/2" digit

1.021,651 V This is the 1 V range,

-045.230 mV This is the 100 mV range,

0.133,256,7 Ω This is the 1 ohm range,

⁄2 digits are displayed.

O.VLD mV

This is an overload indication on the 1 mV range.

Chapter 1 Quick Start

To Rack Mount the Meter

You can mount the meter in a standard 19-inch rack cabinet using one of three optional kits available. Instructions and mounting hardware are included with each rack-mounting kit. Any HP System II instrument of the same size can be rack-mounted beside the HP 34420A meter.

Remove the carrying handle, and the front and rear rubber bumpers, before rack-mounting the meter.

To remove the handle, rotate it to the vertical position and pull the ends o utward.

To remove the rubber bumper, stretch a corner and then slide it off.

Chapter 1 Quick Start

To Rack Mount the Meter

To rack mount a single instrument, order adapter kit 5063-9240.

To rack mount two instruments side-by-side, order lock-link kit 5061-9694 and flange kit 5063-9212.

To install one or two instruments in a sliding support shelf, order shelf 5063-9255, and slide kit 1494-0015 (for a single instrument, also order filler panel 5002-3999).

Front-Panel Operation

This chapter assumes you are familiar with the meter and menu operations. You should also understand how to make connections for the various types of measurements. If you are not familiar with this information, please read chapter 1, "Quick Start", starting on page 11.

This chapter does not give a detailed description of every front-panel key or menu operation. It does, however, give you a good overview of the front-panel menu and the most common front-panel operations. See

chapter 3 “Features and Functions,” starting on page 53, for a complete discussion of the meter’s capabilities and operation.

Chapter 2 Front-Panel Operation

Front-Panel Menu Reference

A: MEASurement MENU

1: DIG FILTER Ø 2: INTEGRATE Ø 3: OCOMP Ω Ø 4: LOW POWER Ω Ø 5: LOW VOLT Ω Ø 6: LoV LIMIT Ω

1: DIG FILTER Selects the digital filter speed. Can be set to FAST, MEDIUM, or SLOW. 2: INTEGRATE Sets the measurement integration time. 3: OCOMP Ω Enables or disables offset compensation for resistance measurements. 4: LOW POWER Ω Enables or disables low power ohms measurements. 5: LOW VOLT Ω Enables or disables voltage limited resistance measurements. 6: LoV LIMIT Ω Sets the voltage limit for voltage limited resistance measurements.

B: TEMPerature MENU

1:PROBE TYPE Ø 2: UNITS Ø 3: RTD TYPE Ø 4:RTD Ro Ø 5:T/C TYPE Ø 6: COLD JUNCT Ø 7:JUNCT TEMP

1: PROBE TYPE Selects thermocouples, thermistors, or RTDs as the temperature probe. 2: UNITS Sets the measurement units to either °C, °F, or Kelvins. 3: RTD TYPE Sets the type of RTD in use. 4: RTD Ro Sets the nominal (0°C) value for the RTD in use. 5: T/C TYPE Selects the type of thermocouple in use. 6: COLD JUNCT S ets the source of the temperature reference junction. 7: JUNCT TEMP Allows direct entry of reference junction temperature.

C: MATH MENU

1: STATS Ø 2: NULL VALUE Ø 3: SCALE GAIN Ø 4 : SCALE OFST

1:STATS Recalls the values of minimum, maximum, standard deviation, average,

peak-to-peak, and number of readings.

2: NULL VALUE Selects independent null settings for voltage on channels 1 and 2, resistance,

and temperature functions.

3: SCALE GAIN Sets the gain for linear scaling of the data. 4: SCALE OFST Sets the offset for linear scaling of data.

D: TRIGger MENU

1: READ HOLD Ø 2: TRIG DELAY Ø 3: N SAMPLES

1: READ HOLD S elects the reading hold sensiti vity band. 2: TRIG DELAY Specifies a time delay between the trigger and the start of the measurement. 3: N SAMPLES Sets the number of samples taken per trigger.

Chapter 2 Front-Panel Operation

Front-Panel Menu Reference

E: SYStem MENU

1: RDGS STOREØ2: SAVED RDGS Ø3: ERRORØ4: TESTØ5: CHART OUT Ø6: CHART SPANØ 7: CHART NULLØ8: DISPLAYØ9: COMMAØ10: PRESETØ11: REVISION

1: RDGS STORE Enables or disables reading memory. 2: SAVED RDGS Recalls readings stored in memory (up to 1024 readings). 3: ERROR Retrieves errors from the error queue (up to 20 errors). 4: TEST Performs a complete self-test or individual self-tests. 5: CHART OUT Enables or disables the chart recorder output (Analog Out). 6: CHART SPAN Sets the chart recorder output range (Analog Out). 7: CHART NULL Sets the chart recorder output offset (Analog Out). 8: DISPLAY Enables or disables the front panel display. 9: COMMA Enables or disables a comma separator between digits in the display. 10: PRESET Returns the meter to factory default settings. 11: REVISION Displays the meter’s firmware revision code.

F: Input / Output MENU

1: HPIB ADDR Ø 2: INTERFACE Ø 3: BAUD RATE Ø 4: PARITY Ø 5: LANGUAGE

1: HP-IB ADDR Sets the HP-IB bus address (0 to 30, default 22). 2: INTERFACE Selects either the HP-IB or RS-232 remote interface. 3: BAUD RATE Sets the baud rate for RS-232 operation. 4: PARITY Selects even, odd, or no parity for RS-232 operation. 5: LANGUAGE Selects interface language, either SCPI or Keithley 181.

G: CALibration MENU *

1: SECURED Ø [1: UNSECURED] Ø [2:CALIBRATE] Ø [3: CHART ZERO] Ø [4 : CHART GAIN] Ø [5: INJECTED I]

* The commands enclosed in square brackets ( [ ] ) are "hidden" unless the meter is UNSECURED for calibration.

Ø6:CAL COUNT Ø 7:MESSAGE

1: SECURED The meter is secured against calibration; enter code to unsecure.

1: UNSECURED The meter is unsecured for calibration; enter code to secure. 2: CALIBRATE Performs a calibration of meter; must be UNSECURED. 3: CHART ZERO Performs a calibration of the chart recorder output zero level. 4: CHART GAIN Performs a calibration of the chart recorder output gain.

5: INJECTED I Performs a calibration to minimize the injected current. 6: CAL COUNT Reads the total number of times the meter has been calibrated. 7: MESSAGE Reads the first 11 characters of a calibration string, if any,

entered from the remote interface.

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

This section is a step-by-step tutorial which shows how to use the front-panel menu. We recommend that you spend a few minutes with this tutorial to get comfortable with the structure and operation of the menu.

The menu is organized in a top-down tree structure with three levels (menus, commands, and parameters). You move down

the menu tree to get from one level to the next. Each of the three levels has several horizontal choices which you can view by moving left right

Commands

Parameters

• To turn on the menu, press

• To

∨ or up

> .

Menus

Shift < (Menu On/Off).

turn off the menu, press Shift < (Menu On/Off), or press any of

the function or math keys on the top row of front-panel keys.

∧

< or

• To execute a menu command, press

• To recall the last menu command that was executed, press

(Menu Recall).

• To turn off the menu at any time without saving changes, press any

function key

If you become confused or get lost at any point during the tutorial, simply turn off the menu and start over again with step 1 for that example.

Auto/Man .

Shift >

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

Messages Displayed During Menu Use

TOP OF MENU -You pressed

∧ while on the menus level; this is

the top level of the menu and you cannot go any higher.

To turn off the menu, press the choices on a level, press

MENUS - You are on the menus level. Press COMMANDS - You are on the commands level. Press

Shift <

< or >

(Menu On/Off). To move across

. To move down a level, press

< or > view the choices.

< or > to view

∨ .

the command choices within the selected menu group. PARAMETER - You are on the parameter level. Press

< or > to view

and edit the parameter for the selected command. MENU BOTTOM - You pressed

∨ while on the parameter level; this is

the bottom level of the menu and you cannot go any lower.

To turn off the menu, press press

∧ .

Shift <

(Menu On/Off). To move up a level,

ENTERED - The change made on the parameter level is saved. This is displayed after you press

Auto/Man (Menu Enter) to execute the command.

MIN VALUE - The value you specified on the parameter level is too small for the selected command. Th e minimum value allo wed is displayed for you to edit.

MAX VALUE - The value you specified on the parameter level is too large for the selected command. The maximum value allowed is displayed for you to edit.

EXITING - You will see th is m essa ge if yo u tu rn of f th e me nu b y pressing

Auto/Man (Menu On/Off) or a front-panel function/math key. You

did not edit an y va lues on th e pa ram et er leve l a nd ch an ge s w ere NO T sa ved . NOT ENTERED - You will see this message if you turn off the menu by

pressing

Shift < (Menu On/Off) or a front-panel function/math key.

You did some editing of parameters but the changes were NOT saved. Press

Auto/Man ( M en u E nt er ) to sa v e c ha ng es made on the paramet er

level. VOLTS ONLY - The requested function is only available for voltage

measurements. UNAVAILABLE - The action requested is NOT allowed in the present configuration.

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

Menu Example 1 The following steps show you how to turn on the menu, move up or down

between levels, move across the choices on each level, and turn off the menu. In this example, you will turn off the display comma separator.

The meter can display readings on the front panel with or without a comma separator. The following steps show how to disable the comma.

- 0.824,153 V - 0.824153 V

With comma separator Without co mma separator

(factory setting)

On/Off

Shift < 1 Turn on the menu.

You enter the menu on the menus level. The MEAS MENU is your first choice on this level.

A: MEAS MENU

> > > > 2 Move across to the SYS MENU choice on this level.

There are six menu group choices available on the menus level. Each choice has a letter prefix for easy identification (

A: , B: , etc.).

E: SYS MENU

∨ 3 Move down to the commands level within the SYS MENU.

The RDGS STORE command is your first choice on this level.

1: RDGS STORE

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

> > > > 4 Move across to the COMMA command on the commands level.

> > > > There are eleven command choices available in the SYS MENU. Each choice

on this level has a number prefix for easy identification (

1: , 2: , etc.).

9: COMMA

∨ 5 Move down a level to the COMMA parameter choices.

The first parameter choice is ON for the COMMA command (the comma setting is stored in non-volatile memory and ON is the factory setting).

> 6 Move across to the OFF choice.

There are two parameter choices for COMMA.

OFF

Auto/Man

ENTER 7 Save the change and turn off the menu.

The meter beeps and displays a message to show that the change is now in effect. You are then exited from the menu. The meter will no longer show commas in the display.

ENTERED

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

Menu Example 2 The following exercise demonstrates how to use the menu recall feature

as a shortcut to set the COMMA command back to its original setting.

You must perform the steps in Menu Example 1 before you start this example.

Recall

Shift > 1 Use menu recall to return to the COMMA command.

This returns you to the COMMA command, which was the last command used before you exited the menu in the Example 1.

9: COMMA

v 2 Move down to the COMMA parameter choices.

The first parameter choice is OFF (the current setting from Example 1).

OFF

> 3 Move across to the ON choice.

Set the parameter back to its original value.

Auto/Man

ENTER 4 Save the change and turn off the menu.

The meter beeps and displays a message to show that the change is now in effect. You are then exited from the menu.

ENTERED

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

Menu Example 3 Some commands in the menu require that you enter a numeric

parameter value. The following steps show you how to enter a number in the menu. For this example, you will set the null value for channel 1 to –30 millivolts.

Make sure the meter has channel 1 selected, is in the dc voltage function,

⁄

and has 6

digits displayed. Connect the four-wire short to the meter

input.

On/Off

Shift < 1 Turn on the menu.

You enter the menu on the menus level. The MEAS MENU is your first choice on this level.

A: MEAS MENU

> > 2 Move across to the MATH MENU choice on this level.

There are six menu group choices available on this level.

C: MATH MENU

v 3 Move down to the commands level within the MATH MENU.

The STATS command is your first choice on this level.

1: STATS

> 4 Move across to the NULL VALUE command.

2: NULL VALUE

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

v 5 Move down to edit the NULL VALUE parameter.

The null value should be 0.000000 V when you come to this point in the menu for the first time. For this example, you will first set the null value

to –0.300000 volts.

Ù0.000,000,0 V

When you see the flashing “∧” on the left side of the display, you can abort

the edit and return to the “commands” level by pressing

v v 6 Make the number negative.

∧

The left most character on the display toggles between +, – , and ^.

– 0.000,000,0 V

> > 7 Move the flashing cursor over to edit the second digit.

Notice that the digit to the right of the decimal point is flashing.

– 0.000,000,0 V

^ ^ ^ 8 Increment the digit until “3” is displayed.

You decrement or increment each digit independently. Neighboring digits are not affected.

– 0.300,000,0 V

Chapter 2 Front-Panel Operation

A Front-Panel Menu Tutorial

> > > > 9 Move the flashing cursor over to the units location.

> > > Notice that the units are flashing on the right side of the display.

– 0.300,000,0 V

v 10 Decrease the displayed number by a factor of 10.

Notice that the position of the decimal point changes and the displayed

number increases by a factor of 10 and the mV annunciator is on.

– 030.000,00 mV

Auto/Man

ENTER 11 Save the change and turn off the menu.

The meter beeps and displays a message to show that the change is now in effect. You are then exited from the menu.

ENTERED

You will be returned to the normal measurement display, and, if you have installed the four-wire short, the display will show a positive measurement in the approximate amount of the null value just entered.

The Null annunciator is on in the display.

Keep in mind that null is turned on and - 0.03 volts is used as the null value for measurements. To clear the null value, press

Null .

Hint You can use the menu recall feature to save steps when entering the null

value. First, press

Null on the front panel and then press Shift >

(Menu Recall). The meter will jump to the 2:NULL VALUE command.

v . The null value in the display is the first reading taken after

Press you turned NULL on. You can then edit this number as described.

This is the end of the front-panel menu tutorial. The remainder of the chapter discusses several of the most common front-panel operations.

Chapter 2 Front-Panel Operation

To Select an Input Channel

For voltage measurements, you have two independent input channels.

TOGGLES MEASUREMENT CHANNEL

(SCAN) ALTERNATING MEASUREMENT CHANNELS

• Pressing

Channel toggles the display between Channel 1 and

Channel 2.

• Pressing

Shift Channel (Scan) creates an alternating Channel 1 and

Channel 2 display. Press

RED

BLACK GREEN

WHITE

Channel again to cancel.

DC Voltage

Channel 1

Channel 2

Scan mode alternates between input channels every 3 seconds or every measurement, whichever is longer. If you are using the scan mode, turn off all the input filters (both digital and analog), see page 55.

Chapter 2 Front-Panel Operation

To Select a Range

You can let the meter automatically select the range using autoranging or you can select a fixed range using manual ranging.

Toggles between autoranging and manual ranging

Selects a higher range and disables autoranging

Selects a lower range and disables autoranging

Man annunciator is on when manual range is enables

• Autoranging is selected at power-on and after a remote interface reset.

• Autorange thresholds:

Down range at <10% of range Up range at >120% of range

• If the input signal is greater than the present range can measure, the

meter will give an overload indication (“OVLD”).

• When making difference or ratio measurements, an overload on either

channel will give an overload indication (“OVLD”).

Chapter 2 Front-Panel Operation

To Set or Change the Number of Digits

You can set the display to show 4

⁄

, 5

⁄

, 6

⁄

book, the most significant digit (leftmost on the display) is referred to as

⁄

the “

” digit, since it can only be a “0” or “1”. The number of digits

displayed also depends upon the integration time set, see page 25.

, or 7

⁄

digits. In this

Press the Shift key

Selects 6 (10 PLC)

Selects 5 (1 PLC)

⁄

digits

• The number of digits is set to 6

Selects 7 (100 PLC)

⁄

digits

⁄

digits

⁄

digits at power-on and after a

remote interface reset.

• The number of digits shown is dependent upon integration time and

filter settings. The meter will not allow you to show more digits than the practical measurement capability of the meter. You can, however, reduce the number of digits shown.

Fewer More Digits Digits

Chapter 2 Front-Panel Operation

To Set the Integration Ti me

To Set the Integration Time

Integration time is specified in Number of Power Line Cycles (NPLC). You can set the NPLC to 0.02, 0.2, 1, 2, 10, 20, 100, or 200. Also see

"Integration Time" on page 58.

• You can set the integration time to one of three fixed values by

choosing the number of digits displayed, see page 43.

• You can set the integration time in the MEASure menu using the

INTEGRATE command.

• The Integration Time is directly related to the maximum number of

digits the meter will display.

NPLC

0.02

0.2 1 2

20 100 200

Digital Filter Off

Max Digits Shown

41⁄2 5 51⁄2 6 61⁄2 7 61⁄2 7

⁄2 7

6 71⁄2 7 71⁄2 7 71⁄2 7

Digital Filter On

Max Digits Shown

⁄2

• You can always select to show fewer digits than the maximum allowed

⁄

(the minimum number of digits shown is 4

Chapter 2 Front-Panel Operation

To Make Null (Relative) Measurements

Each null measurement, also called relative, is the difference between a stored null value and the input signal. See page 77.

Enables null operation; Press again to disable

Reading = measurement – null value

• You can make null measurements on any function or channel. You can

set a null for each channel and function independently. The meter remembers the null value when you switch between input channels or functions.

• To null the test lead resistance for more accurate two-wire ohms

measurements, short the ends of the test leads together and then

Null .

press

• The first reading taken after you press

in the Null Register. Any previously stored value is replaced with the new value.

• After enabling null, you can edit the stored null value by

pressing

VALUE” command in the MATH MENU (only if null is enabled). Go down to the “parameter” level, and then edit the displayed value.

Shift > (Menu Recall). This takes you to the “NULL

Null annunciator is on when null operation is enabled

Null is stored as the null value

Chapter 2 Front-Panel Operation

To Store Minimum and Maximum Readings (Stats )

To Store Minimum and Maximum Readings (Stats)

You can store the minimum and maximum readings during a series of measurements. The following discussion shows how to read the minimum, maximum, average, peak-to-peak, standard deviation, and reading count.

Enables stats operation; Press again to disable

Stats annunciator is on when stats operation is enabled

• You can use stats with any function. When you change functions, stats

operation is disabled.

• Changing input channels or selecting Scan does not disable stats. The

stored readings, however, are not marked as to the input channel.

• After enabling stats, you can read the stored minimum, maximum,

average, standard deviation, peak-to-peak, and count by pressing

Shift > (Menu Recall). This takes you to the “STATS” command in

the MATH MENU (only if stats is enabled). Go down to the “parameter” level pressing

< or > .

• After reading the stored value, pressing

∨

, and then read the values by

Shift < (Menu On/Off)

returns to the measurement display and continues stats operations.

• The stored values are cleared when you turn stats on, turn off the

power, or perform either a remote interface reset or preset.

• The average and standard deviation are of all readings taken since

stats was enabled (not just the average of the stored minimum and maximum). The count is the total number of readings taken since stats was enabled.

Chapter 2 Front-Panel Operation

To Trigger the Meter

You can trigger the meter from the front panel using single trigger or autotrigger.

Enables single trigger and triggers the meter

• Autotriggering is enabled when you turn on the meter. Notice that the

* (sample) annunciator turns on during each measurement.

• Single triggering takes one reading each time you press

then waits for the next trigger. Continue pressing this key to trigger the meter.

Using an External Trigger

The external trigger mode is also enabled by pressing It is like the single trigger mode except that you apply a trigger pulse to the rear-panel negative edge of a TTL pulse.

The front-panel

Toggles between autotrigger and reading hold

Ext Trig

Single key is disabled when in remote.

terminal. The meter is triggered on the

Trig annunciator is on when the meter is waiting for single trigger (autotrigger disabled)

* (sample) annunciator is on

during each measurement

Single and

Single .

Chapter 2 Front-Panel Operation

To Use Reading Hold

The reading hold feature allows you to capture and hold a stable reading on the display. When a stable reading is detected, the meter emits a beep and holds the value on the display.

Toggles between autotrigger and reading hold

• Reading hold has an adjustable sensitivity band to allow you to select

which readings are considered stable enough to be displayed. The band is expressed as a percent of reading on the selected range. The meter will capture and display a new value only after three consecutive readings are within the band.

• The default band is 0.10% of reading. After enabling reading hold,

you can choose a different band by pressing

This takes you to the “READ HOLD” command in the TRIG MENU (only if reading hold is enabled).

Go down to the “parameter” level, and then select a value: 0.01%,

0.10%, 1.00%, or 10.00% of reading.

• The sensitivity band is stored in volatile memory; the meter sets the

band to 0.10% of reading when power has been off or after a remote interface reset.

* (sample) annunciator is on

during each measurement

Shift > (Menu Recall).

Chapter 2 Front-Panel Operation

To Make Voltage Ratio and Difference Measurements

To calculate a voltage ratio, the meter measures the voltages applied

to the Channel 1 input terminals and Channel 2 input terminals. The

calculation is as follows:

Difference = ((Ch 1 voltage − Ch 1 Null ) − (Ch 2 voltage − Ch 2 Null )) − Null *

Ratio =

(Ch 1 voltage − Ch 1 Null )

(Ch 2 voltage − Ch 2 Null )

RED

DC Voltage

CH1 BLACK

CH2 GREEN

DC Voltage

WHITE

DIFFERENCE

RATIO

• Maximum input signal on Channel 1 is 120 Vdc, the meter will

autorange on the actual input or can be manually set.

• Maximum input signal on Channel 2 is 12 Vdc, the meter will

autorange on the actual input or can be manually set.

• Maximum voltage difference between Channel 1 LO and

Channel 2 LO is 150 Vdc.

• Null, if used, is independent for each channel. An additional null* of

the difference can also be made. If null is used on either input channel,

the ‘Null’ annunciator will flash when the difference function is selected. If you null the difference, the ‘Null’ annunciator will be steady.

*The difference null is only available from the front panel.

Chapter 2 Front-Panel Operation

To Use Reading Memory

The meter can store up to 1024 readings in internal memory. The following steps demonstrate how to store readings and retrieve them.

1 Select the function.

Select any measurement function. You can change the function at any time during reading memory.

Single 2 Select the single trigger mode.

Notice that the Trig annunciator turns on. When reading memory is

enabled, readings are stored when you trigger the meter.

For this example, single triggering is used to store readings. You can also use auto triggering or reading hold.

On/Off

Shift < 3 Turn on the menu.

A: MEAS MENU

< < < 4 Move across to the SYS MENU choice on this level.

E: SYS MENU

v 5 Move down to a level to the RDGS STORE command.

1: RDGS STORE

Chapter 2 Front-Panel Operation

To Use Reading Memory

v > 6 Move down a level and then across to the “ON” choice.

Auto/Man

ENTER 7 Save the change and exit the menu.

Notice that the Mem (memory) annunciator turns on to indicate that the

meter is ready to store readings. Up to 1024 readings can be stored in

first-in-first-out (FIFO) order. When memory is full, the Mem

annunciator will turn off.

Readings are preserved until you re-enable reading memory at another time, turn off the power, or perform a remote interface reset.

Single Single Single 8 Trigger the meter three times.

This stores three readings in memory.

Recall

Shift > 9 Use menu recall to retrieve the stored readings.

This takes you to the “SAVED RDGS” command in the SYS MENU.

2: SAVED RDGS

Chapter 2 Front-Panel Operation

To Use Reading Memory

v 10 Move down a level to view the first stored reading.

Reading memory is automatically turned off when you go to the

“parameter” level in the menu.

The first reading displayed is the first reading that was stored (FIFO). If no

readings are stored in memory, “EMPTY” is displayed. The first five digits of the reading and the reading number are displayed. After a brief pause, the reading number is removed and all reading digits are shown.

The stored readings are displayed with their units ( µ, m, k, etc.) when

appropriate. For example:

Reading

number

10.31607K: 11

Units



10.316076 K

> > 11 Move across to view the two remaining stored readings.

The readings are stored horizontally on the “parameter” level.

If you press

last reading and you will know how many readings were stored.

On/Off

Shift < 12 Turn off the menu.

EXITING

< when you first get to the “parameter” level, you will see the

Features and Functions

You will find that this chapter makes it easy to look up all the details about a particular feature of the meter. Whether you are operating the meter from the front panel or from the remote interface, this chapter will be useful.

This chapter is divided into the following sections:

• General Measurement Configuration, page 55

• Voltage Measurement Configuration, page 66

• Resistance Measurement Configuration, page 68

• Temperature Measurement Configuration, page 71

• Math Operations, page 74

• Null (Relative) Operation, page 77

• Reading Hold, page 79

• Triggering, page 80

• System-Related Operations, page 90

• Voltmeter Complete Terminal, page 97

• External Trigger Terminal, page 97

• Chart Output (Analog Output) Operation, page 98

• Remote Interface Configuration, page 101

• Calibration, page 107

• Defaults, Power-On and Reset States, page 112

Some knowledge of the front-panel menu will be helpful before you read this

chapter. If you have not already read chapter 2, “Front-Panel Menu Operation,” starting on page 29, you may want to read it now. Chapter 4, “Remote Interface Reference,” starting on page 115, lists the syntax for the

SCPI (Standard Commands for Programmable Instruments) commands

available to program the meter.

Throughout this manual, the following conventions are used for SCPI command syntax. Square brackets ( [] ) indicate optional keywords or parameters. Braces ( {} ) enclose a list of parameters separated with a vertical bar (|), use only one of the values . Triangle brackets ( <> ) indicate that you must substitute a value for the enclosed parameter.

The actual command string you send to the meter should not include any of the conventions indicated above.

Chapter 3 Features and Functions

General Measurement Configuration

This section contains information to help you configure the meter for making measurements. You may never have to change any of the measurement parameters discussed here, yet they are provided to give you the flexibility you might need.

Input Filters

Two input filters are available; a digital filter and an analog filter. You can enable the digital filter, the analog filter, or both. The digital filter may be used for any measurement type. The analog filter is only available for thermocouple temperature measurements and voltage measurements on the 1 mV, 10 mV, or 100 mV ranges.

TURN FILTERS ON OR OFF

DIGITAL Ø ANALOG Ø ANA + DIG

Chapter 3 Features and Functions

General Measurement Configuration

• Front Panel operation: Press Shift Filter and scroll to one of DIGITAL, ANALOG, or ANA + DIG . Press filter type. Press the

Filter key to turn the filter on or off.

Enter to enable the

To set the digital filter averaging, use the MEASurement menu 1: DIG FILTER command.

• Remote operation: the following commands turn the filters off, on,

set the digital filter count, :

INPut:FILTer

:STATe {OFF|ON} :TYPE {ANAlog | DIGital | BOTH} :DIGital:RESPonse {SLOW|MEDium|FAST} :DIGital:PRECharge {ON | OFF}

Using the filters in remote operation is not recommended. Use:

INPut:FILTer:STATe OFF

to disable the filters. The digital filter is also disabled following a remote reset (*RST) or preset (SYStem:PREset).

Use the math operation (AVERage) commands to obtain a single reading that is the average of a number of readings (see page 148). An example program is shown on page 221 in chapter 6.

If you attempt to use the digital filter in remote operations, be aware of the following special conditions:

The digital filter requires a number of readings to settle (10, 50 or

100). The digital filter readings only occur when the meter is triggered to take a reading. In remote operation a reading is only taken when requested. For example, if you have set the digital filter to MEDIUM (50 readings), you will need to request (trigger) 50 readings from the remote interface before the filter can settle. It is also possible that after 50 readings the digital filter will still not be settled as described in the next paragraph.

The STATus:OPERational:CONDition register contains a bit that indicates the settled/unsettled state of the digital filter on a per reading basis. See page 169 in Chapter 4. You should check the state of this bit for each reading to ensure the digital filter count has not reset (filter reset operation is described in the next section).

Chapter 3 Features and Functions

General Measurement Configuration

Digital Filter

• The digital filter is a moving average (boxcar) filter. Equal weighting

is applied to all readings to calculate the displayed reading.

• Three digital filters are available:

SLOW (average last 100 readings), MEDIUM (average last 50 readings), or FAST (average last 10 readings)

• When the digital filter is enabled, the ‘Filt’ annunciator flashes until

the required number of readings are obtained. The measurement displayed before the ‘Filt’ annunciator is steady is the average of the number of readings taken so far. For example, with the filter set to MEDIUM (average of 50 readings), the measurement displayed after 20 readings will be the average those 20 readings. The ‘Filt’ annunciator will flash until 50 readings have been taken.

• The filter count resets (and the ‘Filt’ annunciator will flash) if the

function, range, integration time, or channel is changed.

• The filter count resets if a reading is outside a set range of the

average. The amount of input reading change required to reset the filter count is:

1mV Range All Other Ranges

FAST

MEDIUM

SLOW

Analog Filter

The analog filter is an 11 Hz, two-pole low pass filter. Use this filter to remove line frequency noise from the input measurement.

• The filter requires approximately 300 milliseconds after the input is

present to settle. Using the filter, therefore, slows the measurement rate significantly.

• Use the analog filter only when line power noise (50/60 Hz) is causing

an overload (OVLD) condition. See page 65.

• The analog filter is available for voltage and thermocouple

temperature measurements. The analog filter is not available for resistance measurements.

• The analog filter is available for the 1 mV, 10 mV, and 100 mV ranges.

± 400 ppm of range ± 100 ppm of range ± 700 ppm of range ± 300 ppm of range

± 2000 ppm of range ± 1000 ppm of range

Chapter 3 Features and Functions

General Measurement Configuration

Integration Time

Integration time is the period during which the meter’s analog-to-digital (A/D) converter samples the input signal for a measurement. Integration time affects the measurement resolution (for better resolution, use a longer integration time), and measurement speed (for faster measurements, use a shorter integration time).

• Integration time is specified in number of power line cycles (

NPLCs).

The choices are 0.02, 0.2, 1, 2, 10, 20, 100, or 200 power line cycles.

The default is 10 NPLCs.

• The integration time is stored in volatile memory; the meter selects 10

NPLC when power has been off or after an interface reset.

• Only the integer number of power line cycles (1, 2, 10, 20, 100 or 200

NPLC) provide normal mode (line frequency noise) rejection.

• Integration time is related to the maximum number of digits the

meter will display. You can always choose to show fewer digits than

⁄

the maximum allowed (the minimum number of digits shown is 4

NPLC

0.02

0.2 1 2

20 100 200

Digital Filter Off

Max Digits Shown

⁄

Digital Filter On

Max Digits Shown

⁄

Chapter 3 Features and Functions

General Measurement Configuration

• Front Panel operation: Integration time can be set indirectly when

you select the number of digits (See page 43).

You can also set the integration time in the MEASurement menu with the 2: INTEGRATE command.

• Remote operation: Refer to the table on page 129. Use one of the

following commands:

[SENSe:]

VOLT:DC:NPLC {0.02|0.2|1|2|10|20|100|200|MIN|MAX} FRES|RES

:NPLC {0.02|0.2|1|2|10|20|100|200|MIN|MAX}

TEMP:NPLC {0.02|0.2|1|2|10|20|100|200|MIN|MAX}

Integration time and resolution are related. The CONFigure and MEASure? commands can also set the integration time, see page 129.

Integration Time is local to the selected function. This means that you can select the integration time for each function independently. The meter remembers the integration time when you switch between functions.

Chapter 3 Features and Functions

General Measurement Configuration

Reducing Measurement Noise

At high resolutions and low measurement levels, measurement noise can become an important factor in the accuracy of your measurements. One possible source of measurement noise is the wiring and cabling in the test setup. These noise sources and their effects are discussed in Chapter 7, "Measurement Tutorial". A smaller level of noise is also inherent in the meter itself.

To minimize the effects of noise on your measurements, use the highest possible integration time (NPLC) and average the readings. Faster reading rates are more susceptible to noise. Choosing the best NPLC and averaging method for your measurement requires a tradeoff between the reading rate and the level of acceptable noise in the resulting measurement.

The Integration Time (NPLC) and averaging can be multiplied to create an equivalent NPLC. The equivalent NPLC defines the reading rate and characterizes the expected noise level. Averaging can be performed in the meter by using either the digital filter or by using the statistics (Stats) mode of operation.

Measurement noise characteristics of the meter closely match theoretical gaussian noise distributions. The graph on the next page shows typical input noise measurements for the 1 mV range with the low thermal shorting plug applied to the input terminals. Other functions and ranges will exhibit similar noise reduction characteristics versus NPLC.

For example, if you set the NPLC to 20 and enable the digital filter set to FAST (10 reading average), the equivalent NPLC is 200. At an equivalent NPLC of 200, the reading rate is approximately 6 readings per minute (digital filter fully settled) and the typical noise level expected is

1.6 nVrms.

Alternately, if you take readings every 5 minutes, you can set an equivalent NPLC of 5000 to minimize the noise in the measurement. An equivalent NPLC of 5000 could be obtained by setting the integration time to 100 NPLC and enabling the digital filter set to MEDIUM (50 reading average). At this equivalent NPLC, a typical noise level of 0.35 nVrms can be expected.

nV rms Noise

Chapter 3 Features and Functions

General Measurement Configuration

30 minute measurement, ±0.5° C, zero input, rms noise (typical)

Equivalent NPLC Approximate

Readings per second

Readings per minute

Minutes per reading

Reading Rate

• Front Panel operation: Integration time can be set indirectly when

you select the number of digits (See page 43).

You can also set the integration time in the MEASurement menu with the 2: INTEGRATE command.

Enable the digital filter and set the filter reading average as described on page 55.

• Remote operation: Set the integration time for the measurement

function. If possible, use NPLC 200. If you use the CONFigure or MEASure commands, refer to the table on page 129.

Use the math operations (AVERage) to average the readings or average the readings in your program. An example program that uses the math operations to average readings is shown on page 221 in Chapter 6. Do not use the digital filter to average readings, see page 56.

Chapter 3 Features and Functions

General Measurement Configuration

Number of Digits Displayed

Front Panel operation only. See also “Integration Time,” on page 58.

• You can set the number of digits shown in the display to 4, 5, 6, or 7

⁄

full digits, plus a “

” digit which can only be a “0” or “1”.

• You can set both the number of digits displayed and the Integration

Time in a single operation by pressing digits keys (see page 43).

• You can change the number of digits displayed without disturbing

the Integration Time settings by pressing the

< or > keys

(see page 43).

⁄

• The number of digits is set to 6

digits at power-on and after either a

remote interface reset or preset.

• The number of digits shown is dependent upon integration time and

filter settings. The meter will not allow you to show more digits than the practical measurement capability of the meter. You can, however, reduce the number of digits shown. The minimum number of digits

⁄

available is 4

. (See the table on page 58).

7 digits

Chapter 3 Features and Functions

General Measurement Configuration

⁄

" digit

6 digits

⁄

" digit

5 digits

⁄

"digit

0.003,256,4 Ω This is the 1 ohm range,

⁄

digits are displayed.

0.216,569 mV This is the 1 mV range,

⁄

digits are displayed.

-045.231 mV This is the 100 mV range,

⁄

digits are displayed.

Chapter 3 Features and Functions

General Measurement Configuration

Ranging

You can let the meter automatically select the range using autoranging or you can select a fixed range using manual ranging. Autoranging is convenient because the meter automatically selects the appropriate range for each measurement. However, you can use manual ranging for faster measurements since the meter does not have to determine which range to use for each measurement.

• The selected mode (auto or manual range) is stored in volatile

memory; the meter returns to autoranging when power has been off or after a remote interface reset.

• Autorange thresholds:

Down range at <10% of range Up range at >120% of range

• If the input signal is greater than the present range can measure, the

meter gives an overload indication: “OVLD” from the front panel or

“9.90000000E+37” from the remote interface.

• For ratio and difference measurements, the specified range is

independent for both Channel 1 and Channel 2.

^ v Auto/ Man • Front Panel operation: Press a front-panel RANGE key to set

manual ranging and to up or down range. Press the Auto/Man key to return to autoranging. See also “To Select a Range,” on page 42.

• Remote operation: Range is set with parameters in the MEASure

and CONFigure subsystems. For example:

CONF:VOLT:DC 10.0

Range can be set directly with the SENSe subsystem. For example:

SENS:VOLT:DC:RANGe 0.001 SENS:RES:RANGE:AUTO

Sets the 10 Volt DC ra nge

Sets the 1 mV DC range Sets auto ranging on 2-wire resistance measurements

Chapter 3 Features and Functions

General Measurement Configuration

Overload Detection

The HP 34420A uses both an analog and digital method to generate an overload condition and display the OVLD message. An understanding of the cause of the overload can help you make more accurate measurements.

Digital Overload Detection

The digital overload detect occurs when the magnitude of the measurement is greater than 120% of the Range. For example,

on the 1 volt Range, signal levels of greater than an OVLD in the display.

Analog Overload Detection

Another type of overload can result in measurement errors that are hard to identify. For example if an overload signal only occurs for a portion of the measurement period, the input amplifier could become non-linear resulting in an inaccurate reading. The displayed result may appear to be correct because the overload signal only occurred during a small portion of the measurement cycle. The HP 34420A detects this problem by providing comparators on the input amplifier. If signals large enough to overload the input amplifier are detected, the display will read OVLD. The comparators detect signals greater than 140% of the range setting.

1.2 volts will cause

If an overload occurs, two solutions are possible.

• Setting the meter to the next higher range will provide 10 times

improvement in the overload signal handling capability. For example,if you are measuring on the 1 mV range and have 2 mV rms of power line (50 or 60 Hz) pickup, the noise overload comparators would sense the peaks of the signals and an OVLD message would be displayed. If you set the range to 10 mV, the resolution (with 7 digits) is still 1 nanovolt, and the reading rate is faster than if ANALOG FILTER had been turned on. Additionally, the 10 mV range noise is almost as low as the 1 mV range.

• Alternately, if using the 1 mV, 10 mV, or 100 mV ranges, turn on the

ANALOG FILTER. The reading rate slows down with the filter on. In the case of a larger overloads (for example, 20 mV rms noise on the 1 mV range) using the ANALOG FILTER would give a lower noise result than changing to the 100 mV range.

Chapter 3 Features and Functions

Voltage Measurement Configuration

Input Channels

The meter has two independent input channels for measuring dc Volts. You can make measurements on either or both channels, measure the difference between the channels, or measure the ratio between the channels. Each channel has an independent settings for null and range.

The figure on page 19 shows connections for two input channels.

• Channel 1 is the default input channel. Both channels use the same

integration time setting.

• The maximum measurable input on Channel 1 is 120V, on

Channel 2 is 12 V.

• For two channel operation, the maximum voltage difference between Channel 1 LO and Channel 2 LO is ±150 V.

• For either channel, the maximum non-destructive input is ±150 V.

• If you enable input filters, the filters are active for both input

channels. Switching between the channels will reset the digital filter reading count (see page 57).

Channel • Front Panel operation: Toggle the input channel by pressing the

Channel key on the front panel. The CH1 or CH2 annunciator will light in the display. The meter keeps range and null settings independently for each channel.

Scan

Shift Channel Choose the scan mode to alternately show the CH1 and CH2 readings.

Disable the digital filter when using the scan mode. In scan mode, the meter alternates between the CH1 and CH2 readings every 3 seconds or for each measurement (whichever is longer).

Chapter 3 Features and Functions

Voltage Measurement Configuration

• Remote operation: The CONFigure and MEASure subsystems use

an optional parameter to specify the input channel as either 1 or 2:

CONF:VOLT:DC DEF, DEF,(@FRONTl) CONF:VOLT:DC DEF, DEF,(@FRONT2)

The SENSe subsystem uses a keyword modification to indicate the channel:

Channel 1 operation Channel 2 operation

SENS1:VOLT:DC:RANG:AUTO SENS2:VOLT:DC:RANG:AUTO

Two Channel Measurements

Ch1 - Ch2 • Difference measurements: First, set the range and null value for

each input channel. Then, select difference measurements.

Difference = ((Ch 1 voltage − Ch 1 Null ) − (Ch 2 voltage − Ch 2 Null )) − Null*

Shift Ch1- Ch2 • Ratio measurements: First, set the range and null value for each

input channel. Then, select ratio measurements.

Ratio =

• Remote operation: use the following commands to measure or

configure a difference or ratio measurement. Set each channel to the appropriate range and null conditions using:

[SENSe1: | SENSe2:]

Then use the following commands to measure the ratio or difference:

(Ch 1 voltage

(Ch 2 voltage − Ch 2 Null )

VOLTage:DC

:RANGE < :NULL:STATe {OFF | ON} :NULL:VALue {<

− Ch 1 Null )

range

value

> | MIN | MAX}

Channel 1 operation Channel 2 operation

MEASure:VOLTage:DC

:RATIO? :DIFFerence?

CONFigure:VOLTage:DC

:RATIO

:DIFFerence [SENSe:]FUNCtion "VOLTage:RATio" [SENSe:]FUNCtion "VOLTage:DIFFerence"

*Difference Null is only available from the Front Panel.

Chapter 3 Features and Functions

Resistance Measurement Configuration

The meter can make 2-wire or 4-wire ohms measurements. The meter can compensate for voltages in the resistive circuit being measured using offset compensation. You can also choose to either limit the power applied or limit the open circuit voltage applied during a resistance measurement.

The test current sourced by the meter depends upon the range and conditions as shown below:

Range Test current

2-wire or 4-wire

measurements

1Ω

10 Ω

100 Ω

1 kΩ

10 kΩ 100 µA10 µA

100 kΩ*10 µA5 µA

1 MΩ*5 µA5 µA

* Offset Compensation is not applied to measurements on these ranges

10 mA 10 mA Not Available 10 mA 10 mA 1 mA 10 mA 1 mA

1 mA

4-wire measurements

Low Power Voltage Limited

100 µA

100 µA Not Available Not Available Not Available Not Available

Chapter 3 Features and Functions

Resistance Measurement Configuration

Offset Compensated Measurements

Offset compensation removes the effect of any voltages in the circuit being measured. The technique involves taking two measurements, one with the current source turned on, and one with the current source turned off and computing the difference. A description of this operation is given on page 259.

• Front Panel operation: Offset compensation is on at power on. Turn offset compensation off under the 3: OCOMP Ω command in the MEASure menu.

• Remote operation: Offset compensation is off following a remote reset or preset. Use the following command to change the state of offset compensation:

SENSe:

FRESistance:OCOMpensated {OFF|ON} RESistance:OCOMpensated {OFF|ON}

Low Power Measurements

Low Power measurements use a reduced output measurement current to limit the power dissipation in the circuit being measured.

• Low Power measurements apply only to 4-wire ohms measurements.

• When the low power measurement mode is enabled, the ‘LP’

annunciator is on in the display.

• Setting the Voltage Limited measurement mode will cancel the Low Power mode.

• Front Panel operation: set low power mode under the

4: LOW POWER Ω command in the MEASure menu.

• Remote operation: use the following command to set the low power

ohms mode:

SENSe:FRESistance:POWer:LIMit {OFF|ON}

Chapter 3 Features and Functions

Resistance Measurement Configuration

Voltage Limited Measurements

Voltage limited resistance measurements clamp the open circuit voltage to predefined limits.

• Voltage limits apply only to 4-wire ohms measurements.

• Voltage limited resistance measurements are only available on

the 10 Ω and 100 Ω ranges. If a manual range is selected in either 2-wire or 4-wire ohms, and then Voltage Limited measurements are enabled, the range will be set to the highest valid range (either 10 Ω or 100 Ω ).

• The open circuit voltage can be limited to 20 mV, 100 mV, or 500 mV.

• Setting the Low Power measurement mode will cancel the

Voltage Limited mode.

• Front panel operation: Enable or disable the voltage limit under the 5: LOW VOLT Ω command in the MEASure menu.

Set the voltage limit under the 6: LoV LIMIT Ω command in the MEASure menu.

• Remote operation: the following command enables or disable the low voltage limit mode:

SENSe:FRESistance:VOLTage:LIMit {OFF|ON}

Set the limit with the following command:

value

SENSe:FRESis tanc e:VO LTag e: LIMi t:VA Lue {<

>|MIN|MAX}

Chapter 3 Features and Functions

Temperature Measurement Configuration

This section contains information to help you configure the meter for making temperature measurements. To measure temperature, you will need a temperature transducer. Transducer descriptions and specific comments about their usage are given on page 263. The meter supports three general categories of transducer:

• RTD (Resistive Temperature Device)

• THERM (Thermistor)

• T/C (Thermocouple)

The meter supports specific types of transducers in each category:

RTD’s R

= 4.9 Ω to 2.1 kΩ

α = 0.00385 (DIN/IEC 751) α = 0.00391

Once you set the measurement units, probe type, and transducer type, the setting is stored in non-volatile memory. This makes the last probe type used the default probe type.

Thermistor Thermocouples

5k Ω

B, E, J, K, N, R, S, T

Measurement Units

• The meter can report temperature in °C (Celsius), °F (Fahrenheit),

or K (Kelvins).

• The measurement units set are stored in non-volatile memory.

• Front Panel Operation: Set the units under the 2: UNITS command

in the TEMPerature menu.

• Remote operation: Set the units using the following command:

UNIT:TEMPerature {C|F|K}

Chapter 3 Features and Functions

Temperature Measurement Configuration

RTD Measurements

• The meter supports RTDs with α = 0.00385 (DIN/IEC 751) or α = 0.00391. The nominal value of the RTD (R of 4.9 Ω to 2.1 kΩ. RTD Connections are shown on page 21.

• The meter makes a 4-wire measurement for RTD’s. All four input leads must be connected.

• Front Panel operation: Set RTD as the probe type under the 1: PROBE TYPE command in the TEMPerature menu.

Select the RTD type under the 3: RTD TYPE command in the TEMPerature menu.

) must be in the range

Enter the 0° C resistance of the RTD (R in the TEMPerature menu.

• Remote operation: Use the following commands for temperature measurements with RTD’s:

CONFigure:TEMPerature FRTD,{85|91}[,1,< MEASure:TEMPerature? FRTD, {85|91}[,1,< SENSe:FUNCtion "TEMPerature" SENSe:TEMPerature:TRANsducer:TYPE FRTD SENSe:TEMPerature:TRANsducer:FRTD:TYPE {85|91} SENSe:TEMPerature:TRANsducer:FRTD:RESistance <

) in the 4: RTD R0 command

resolution resolution

value

>] >]

Thermistor Measurements

• Only the 5 kΩ thermistor type is supported. Thermistor connections

are shown on page 21.

• The thermistor must be connected to the Channel 1 inputs.

• Front Panel operation: Set THERM as the transducer type under

the 1: PROBE TYPE command in the TEMPerature menu.

• Remote operation: use the following commands for temperature measurements with a thermistor:

CONFigure:TEMPerature THER, DEF,[,1,< MEASure:TEMPerature? THER, DEF,[,1,< SENSe:FUNCtion "TEMPerature" SENSe:TEMPerature:TRANsducer:TYPE THER

resolution

Chapter 3 Features and Functions

Temperature Measurement Configuration

Thermocouple Measurements

• The thermocouple must be connected to the Channel 2 inputs. Be sure

to observe the correct polarity. Thermocouple connections are shown on

page 22.

• Thermocouple measurements require a reference junction

temperature. You can input a known fixed junction temperature, use an external thermistor temperature, or use the internal thermistor temperature as the reference junction temperature.

The accuracy of the measurement is very dependent upon the thermocouple connections and the reference junction temperature. Use a fixed temperature reference for highest accuracy measurements. The internal thermistor reference produces the lowest accuracy measurements. See page 265 for a discussion of the reference junction temperature measurements.

• Front Panel operation: Set T/C as the probe type under the

1: PROBE TYPE command in the TEMPerature menu.

Select the thermocouple type under the 4: T/C TYPE command in the Temperature menu.

Set the reference junction temperature source under the 5: COLD JUNCT command in the TEMPerature menu.

If you used a FIXed reference junction temperature, set the reference temperature under the 6: JUNCT TEMP command in the TEMPerature

menu. The number entered must be in the range of –1° C to 55° C.

• Remote operation: use the following commands for temperature

measurements using thermocouples:

CONFigure:TEMPerature TC,{B|E|J|K|N|R|S|T}[,1,< MEASure:TEMPerature? TC,{B|E|J|K|N|R|S|T}[,1,< SENSe:

FUNCtion "TEMPerature" TEMPerature:TRANsducer

:TYPE TC :TCouple

:TYPE {B|E|J|K|N|R|S|T} :RJUNction:TYPE {FIXed|INTernal|THERmistor} :RJUNction {<

reference

>|MIN|MAX}

resolution

Chapter 3 Features and Functions

Math Operations

There are two math operations available, only one of which can be enabled at a time. You can choose to either scale the readings as they are taken, or keep statistics on a group of readings. The selected math operation remains in effect until you disable it, change functions, turn off the power, or perform a remote interface reset.

Scaling

• The scaling is applied as:

reading = gain ∗ (measurement − offset)

Scale

Shift Stats • Front Panel operation: Set the values of gain and offset in the

MATH menu. Enable scaling by pressing the scale key. The Stats annunciator will light in the display.

• Remote operation: the math operations and registers are controlled using commands within the CALCulate command subsystem. First, select the math operation you want to use

CALCulate:FUNCtion SCALe

Then, set the values for gain and offset.

gain

CALCulate:SCALe:GAIN < CALCulate:SCALe:OFFSet <

Finally, enable the selected math function by turning the math state on:

CALCulate:STATe ON

offset

Chapter 3 Features and Functions

Math Operations

Statistics

• After you enable statistics, the first reading that the meter takes is

stored as both the minimum and maximum value. The minimum is replaced with any subsequent value that is less. The maximum is replaced with any subsequent value that is greater.

• All values are stored in volatile memory; the meter clears the values

when stats is turned on, when power has been off, or after a remote interface reset or preset.

• When enabled, the following statistics are available:

MIN minimum reading MAX maximum reading AVER arithmetic average of all readings STD DEV standard deviation of all readings

PEAK – PEAK peak to peak value of minimum and maximum COUNT the total number of readings

• Front Panel operation: Enable the statistics by pressing

Stats key. Read the statistics gathered in the MATH menu

the

under the STATS command.

After reading the stored statistics, press

return to the measurement and continue taking statistics.

Shift < (Menu On/Off) to

Chapter 3 Features and Functions

Math Operations

• Remote operation: the math operations and registers are controlled using math operation commands. First, select the math operation you want to use

CALCulate:FUNCtion AVERage

Then, enable the selected math function by turning the math state on:

CALCulate:STATe ON

When you have finished collecting readings, obtain the desired statistics:

CALCulate:AVERage

:MINimum? :MAXimum? :AVERage? :SDEViation? :PTPeak? :COUNt?

After reading the statistics, supply another trigger to continue taking measurements and collecting statistics. Measurements are not taken while reading the results.

If you are interested in the statistics on a number of readings, but not the readings themselves, you can use the following command:

DATA:FEED RDG_STORE, ""

The null value parameter in the command tells the meter not to store the individual readings. The meter does, however, accumulate statistics on the readings. This method removes the 1024 reading limitation and you can calculate statistics on any number of readings.

See page 150 for more information.

Chapter 3 Features and Functions

Null (Relative) Operation

When making null measurements, also called relative, each reading is the difference between the input signal and a stored null value. You could, for example, make a more accurate two-wire ohms measurement by shorting the test leads and pressing resistance. See also “To Make Null (Relative) Measurements,” on page 45.

Reading = measurement – null value

• The null value is adjustable and you can set it to any value between 0 and ± 120% of the highest range, for the present function.

Null to remove the test lead

• The null value is stored in volatile memory; the value is cleared when power has been off or after a remote interface reset.

• Each function and channel has an independent null value. For voltage measurements, each input channel has an independant null. Temperature measurement null is applied to all temperature measurements (if you change the probe type, null is still enabled and applied). The null for resistance measurements applies to both 2-wire and 4-wire measurements.

• The null value is stored in the meter’s Null Register. There are two

ways you can specify the null value. First, you can enter a specific number into the register from the front-panel menu or from the remote interface. Any previously stored value is replaced with the new value.

If you are operating the meter from the front panel, entering a null value also turns on the null function.

The second way to enter the null value is to let the meter store the first reading in the register. Press the displayed measurement the null value and enable the Null operation. After you enable null, the first reading displayed will be zero. If you entered a number into the register, as described in the paragraph above, the first reading does not overwrite the stored value.

• Since an independent null value is stored for each input channel, difference or ratio functions also use these null values. Additionally, when using the difference function, an additional difference null can be applied (the difference null is only available from the front panel).

See page 67 for a description of how null is applied to difference and ratio functions.

Null key to make the

Chapter 3 Features and Functions

Null (Relative) Operation

• Front-panel operation: After enabling null, you can edit the stored

null value by pressing value is replaced with the new value. Turning on the menu does not disable the null operation; the meter will resume taking measurements when you turn off the menu.

When null is enabled, the Null annunciator lights in the display. For ratio or difference measurement, if either input channel has a null enabled, the Null annunciator will flash. If you apply the difference null, the Null annunciator will light (not flash).

• Remote interface operation: You can use the following commands

to make null measurements. Null must be enabled before you can store

a value in the Null Register.

SENSe1 | SENSe2

:VOLTage:DC

:NULL {OFF|ON} :NULL {<

[SENSe:]

FRESistance | RESistance

:NULL { OFF | ON } :NULL {<

TEMPerature

:NULL { OFF | ON } :NULL {<

Shift > (Menu Recall). Any previously stored

value

>|MIN|MAX}

To enable null and set a null value (0.10) for the 2-wire resistance function execute the following commands in the order shown.

SENS:RES:NULL ON SENS:RES:NULL 0.10

You can use the first reading as a null value from the remote interface by first setting the function, range, and resolution and then executing the following command:

[SENSe:]NULL [{OFF | ON | ONCE}]

Chapter 3 Features and Functions

Reading Hold

The reading hold feature allows you to capture and hold a stable reading on the front-panel display. This is especially useful in situations where you want to take a reading, remove the test probes, and have the reading remain on the display. When a stable reading is detected, the meter beeps and holds the reading on the display.

The reading hold feature is available only from the front panel. If you go to remote when reading hold is enabled, the meter ignores it; when you return to local (front panel), reading hold is enabled again.

• Reading hold has an adjustable sensitivity band (adjustable only from the front panel) to allow you to select which readings are considered stable enough to be displayed. The band is expressed as a percent of reading, on the selected range. The meter will capture and display a new value only after three consecutive readings are within the band.

Select one of these values: 0.01%, 0.10% (default), 1.00%, or 10.0% of reading.

For example, assume that the 1.00% band is selected and a 5 volt signal is applied to the meter. If three consecutive readings are between 4.95 volts and 5.05 volts, the meter will beep and display a new reading.

• The sensitivity band is stored in volatile memory; the meter sets the band to 0.10% when power has been off or after an interface reset.

• If the meter is in autorange when you enable reading hold, it will autorange to the correct range. If the meter is in the manual range mode, the same fixed range will be used for reading hold.

• For certain applications, it may be useful to use reading hold with reading memory. See also “Reading Memory,” on page 90.

• Front Panel operation: After enabling reading hold, you can select

a different sensitivity band by pressing

Shift > (Menu Recall).

1: READ HOLD

Chapter 3 Features and Functions

Triggering

The meter’s triggering system allows you to generate triggers either manually or automatically, take multiple readings per trigger, and insert a delay before each reading. Normally, the meter will take one reading each time it receives a trigger, but you can specify multiple readings (up to 50,000) per trigger.

• You can trigger the meter from the front panel, with an external

trigger, or use autotriggering. Single triggering takes one reading each time you press the triggering, but the meter waits for a pulse on the rear-panel Ext Trig (external trigger) terminal before taking a reading. Autotriggering takes continuous readings at the fastest rate possible for the present configuration. See also “To Trigger the Meter,” on page 47.

Single key. External triggering is like single

• Press

Triggering the meter from the remote interface is a multi-step process that offers triggering flexibility.

• First, you must configure the meter for the measurement by selecting

the function, range, integration time, etc.

• Then, you must specify the source from which the meter will accept

the trigger. The meter will accept a software (bus) trigger from the remote interface, a hardware trigger from the Ext Trig terminal, or an immediate internal trigger.

• Then, you must make sure that the meter is ready to accept a trigger

from the specified trigger source (this is called the wait-for-trigger state).

• Finally, to make the measurement, you must provide an INITiate,

READ?, or MEASure command.

The diagram on the next page shows the meter’s triggering system.

Shift Auto/Hold to return the meter to auto triggering.

Initiate Triggering

MEASure? READ? INITiate

Trigger Source

TRIGger:SOURce IMMediate TRIGger:SOURce EXTernal TRIGger:SOURce BUS front-panel "Single" key

Trigger Delay

TRIGger:DELay

Chapter 3 Features and Functions

Triggering

Idle State

Wait-for Trigger State

Delay

Sample (*) Annunciator

Measurement Sample

Triggering the meter is a multi-step process.

Yes Yes

Sample Count >1

Trigger Count >1

Chapter 3 Features and Functions

Triggering

Trigger Source Choices

You must specify the source from which the meter will accept a trigger.

• The trigger source is stored in volatile memory; the source is set to

autotrigger (front panel) or immediate (remote interface) when power has been off or after a remote interface reset.

• Front Panel operation: the meter will accept a either a front panel

single trigger or a hardware trigger from the Ext Trig terminal, or continuously take readings using autotrigger. At power-on, autotriggering is used.

• Remote operation: the meter will accept a software (bus) trigger, a

hardware trigger from the Ext Trig terminal, or an immediate internal trigger. See "Triggering" on page 80 for more information.

Autotriggering In the autotrigger mode (front panel only), the meter continuously takes readings at the fastest rate possible for the present configuration. This is the power-on trigger source for front-panel operation.

Single Triggering In the single trigger mode (front panel only), you can manually trigger the meter by pressing reading, or the specified number of readings (sample count), each time you press the key. The

‘Trig’ annunciator turns on when the meter is

waiting for a trigger.

Single . The meter takes one

Pressing the

Single key also allows the meter to accept triggers on the

Ext Trig terminal.

The front-panel

Single key is disabled when in remote.

Chapter 3 Features and Functions

Triggering

External Triggering In the external trigger mode, the meter will accept a hardware trigger applied to the Ext Trig terminal. The meter takes one reading, or the specified number of readings (sample count), each time Ext Trig receives a low-true pulse.

See also “External Trigger Terminal,” on page 97.

• The meter buffers one external trigger. This means that if the meter is taking a reading and another external trigger occurs, that trigger is

accepted (a “Trigger ignored” error is not reported). After the reading in progress is complete, the stored trigger satisfies the trigger source and then the trigger is issued.

• Front-panel operation: The external trigger mode is like the single

trigger mode except that you apply the trigger to the Ext Trig terminal. Pressing

enables the external trigger mode. The

when the meter is waiting for an external trigger.

Single to enable the single trigger mode also

‘Trig’ annunciator turns on

The front-panel

• Remote operation: Use the following command to enable external trigger.

TRIGger:SOURce EXTernal

Single key is disabled when in remote.

Chapter 3 Features and Functions

Triggering

Internal Triggering In the internal trigger mode (remote interface only), the trigger signal is always present. When you place the meter in the wait-for-trigger state, the trigger is issued immediately. This is the power-on trigger source for remote interface operation.

To select the internal trigger source, send the following command. The CONFigure and MEASure? commands automatically set the trigger source to IMMediate.

TRIGger:SOURce IMMediate

After setting the source to IMMediate, an INITitate or a READ? command will trigger the measurement.

Software (Bus) Triggering The bus trigger mode is available only from the remote interface. This mode is similar to the single trigger mode from the front panel, but you trigger the meter by sending a bus trigger command.

• To select the bus trigger source, send the following command.

TRIGger:SOURce BUS

• To trigger the meter from the remote interface (HP-IB or RS-232),

send the *TRG (trigger) command. The *TRG command will not be accepted unless the meter is in the wait-for-trigger state.

• You can also trigger the meter from the

HP-IB interface by sending the

IEEE-488 Group Execute Trigger (GET) message. The meter must be in the wait-for-trigger state. The following statement shows how to send a GET from a Hewlett-Packard controller.

TRIGGER 722 (group execute trigger)

Chapter 3 Features and Functions

Triggering

The Wait-for-Trigger State

After you have configured the meter and selected a trigger source, you must place the meter in the wait-for-trigger state. A trigger will not be accepted until the meter is in this state. If a trigger signal is present, and if meter is in the “wait-for-trigger” state, the measurement sequence

begins and readings are taken.

The “wait-for-trigger” state is a term used primarily for remote interface operation. From the front panel, the meter is always in the “wait-fortrigger” state and will accept triggers at any time, unless a measurement is already in progress.

You can place the meter in the “wait-for-trigger” state by executing any of the following commands from the remote interface.

MEASure? READ? INITiate

Halting a Measurement in Progress

You can send a device clear at any time to halt a measurement in progress and place the meter in the “idle state.” The following statement shows how to send a device clear from a Hewlett-Packard controller if you are using the HP-IB interface. See also page 187.

CLEAR 722 (device clear)

For operation with the RS-232, you must establish a means to send a device clear (for example, by pressing ^C (Control C)).

A device clear does not affect the configuration of the triggering system. The trigger source, sample count, trigger delay, and number of triggers are not changed.

If you have set the meter to infinite sampling (TRIGger:COUNt INFinity), the device clear is the only way to halt the measurements.

Chapter 3 Features and Functions

Triggering

Number of Samples

Normally, the meter takes one reading (or sample) each time it receives a trigger from the selected trigger source (if the meter is in the wait-for-trigger state). You can, however, instruct the meter to take multiple readings for each trigger received.

• Number of samples: 1 to 50,000. The default is 1 sample per trigger.

• The sample count is stored in volatile memory; the meter sets the

sample count to 1 when power has been off or after a remote interface reset. The CONFigure and MEASure? commands automatically set the sample count to 1.

• Front Panel operation: set the number of samples per trigger in the 3: N SAMPLES command under the TRIGger menu.

• Remote operation: use the following command:

value

SAMPle:COUNt {<

>|MIN|MAX}

Number of Triggers

Normally, the meter will accept only one trigger before returning to the

“idle” trigger state. You can, however, instruct the meter to accept multiple triggers.

This feature is available only from the remote interface. If you set the trigger count and then go to local (front panel), the meter ignores the trigger count setting; when you return to remote, the trigger count returns to the value you selected.

• The selected number of triggers is stored in volatile memory; the meter sets the trigger count to 1 when power has been off or after a remote interface reset or preset. The CONFigure and MEASure? commands automatically set the trigger count to 1.

• The number of triggers can be set to any number between 1 (MIN) and 50000 (MAX) or can be set to be INFinity. When the trigger count is set to be infinite, use the READ? command to collect the readings. Send a device clear to stop the measurements. See page 187 for

information about device clear.

value

TRIGger:COUNt {<

>|MIN|MAX|INFinity}

Chapter 3 Features and Functions

Triggering

Trigger Delay

You can insert a delay between the trigger signal and each sample that follows. This may be useful in applications where you want to allow the input to settle before taking a reading, or for pacing a burst of readings. If you do not specify a trigger delay, the meter automatically selects a delay for you.

• Delay range: 0 to 3600 seconds. The default trigger delay is

automatic; the delay is determined by function, range, and integration

time (see also “Automatic Trigger Delays,” on page 89).

• The trigger delay is stored in volatile memory; the meter selects an

automatic trigger delay when power has been off or after a remote interface reset. The CONFigure and MEASure? commands set the trigger delay to automatic.

• If you specify a delay other than automatic, that same delay is used for

all functions and ranges.

• If you have configured the meter to take more than one reading per

trigger (sample count > 1), the specified trigger delay is inserted between the trigger and each reading.

• Front Panel operation: You can use an automatic trigger delay or

you can specify a delay in seconds. Set the delay time in the 2: TRIG DELAY command of the TRIGger menu.

If an automatic trigger delay is enabled, “AUTO” is displayed momentarily before the actual number of seconds is displayed.

AUTO

Chapter 3 Features and Functions

Triggering

• Front Panel operation (continued)

To set the delay to 0 seconds, select the “parameter” level of the TRIG DELAY command. Move the flashing cursor to the “units” location on the right side of the display. Press ZERO DELAY is reached, then press

Enter .

∨ until

ZERO DELAY

• To select the automatic trigger delay, select the “parameter” level of

the TRIG DELAY command. Move the flashing cursor to the “units” location on the right side of the display. Press AUTO DELAY is reached, then press

Enter .

∨ until

AUTO DELAY

• Remote operation:

You can use the following command to set the trigger delay.

TRIGger:DELay {<

seconds

>|MIN|MAX}

You can use the following command to set an automatic trigger delay.

TRIGger:DELay:AUTO {OFF|ON}

Chapter 3 Features and Functions

Triggering

Automatic Trigger Delays

If you do not specify a trigger delay, the meter selects an automatic delay for you. The delay is determined by function, range, and integration time.

• DC voltage :

Range

V to 120 V

NPLC < 1 Trigger Delay

15 ms

1.0 ms

• Resistance (2-wire and 4-wire):

Range NPLC < 1

Trigger Delay

Ω

1 10 Ω 100 Ω 1 kΩ 10 kΩ 100 kΩ 1 MΩ

1.0 ms

1.0 ms 4 ms 40 ms

• Temperature:

NPLC < 1 Trigger Delay

RTD THERmistor ThermoCouple

1.0 ms

NPLC ³ 1 Trigger Delay

15 ms

1.5 ms

NPLC ³ 1 Trigger Delay

1.5 ms

1.5 ms 6 ms 60 ms

NPLC ³ 1 Trigger Delay

1.5 ms

Chapter 3 Features and Functions

System-Related Operations

This section gives information on topics such as reading memory, errors, self-test, and front-panel display control. This information is not directly related to making measurements but is an important part of operating the meter.

Reading Memory

The meter can store up to 1024 readings in internal memory. Readings are stored in first-in-first-out ( the first reading stored. See also “To Use Reading Memory,” on page 50.

• You can use reading memory with all functions, math operations, and also reading hold. After you have enabled reading memory, you can change the function or input channel. Be aware, however, that the

function labels and channel labels ( reading.

• Readings taken while reading memory is enabled are stored in volatile memory; the meter clears the stored readings when reading memory is turned on again, when power has been off, after a self-test, or after a remote interface reset.

FIFO) order. The first reading returned is

V, OHM, etc.) are not stored with the

• You can use reading memory with autotrigger, single trigger, external trigger, and reading hold. If you configure the meter for multiple readings per trigger, the specified number of readings are stored in memory each time a trigger is received.

Chapter 3 Features and Functions

System-Related Operations

• Front-panel operation: enable readings storage under the

1: RDGS STORE command in the SYStem menu. The ‘Mem’ annunciator lights in the display.

Recall the stored readings under the 2: SAVED RDGS command in the SYStem menu. Press memory to quickly go to the Saved Readings command.

Reading memory is automatically turned off when you go to the

“parameter” level in the menu to recall the readings.

• Remote interface operation: The INITiate command uses reading

memory to store readings prior to a FETCh? command. You can query the number of stored readings in memory by sending the DATA:POINts? command from the remote interface.

Shift > (Menu Recall) after enabling reading

Chapter 3 Features and Functions

System-Related Operations

Error Conditions

When the front-panel ‘ERROR’ annunciator turns on, one or more command syntax or hardware errors have been detected. A record of up

to 20 errors is stored in the meter’s error queue. See chapter 5, “Error Messages,” for a complete listing of the errors.

• Errors are retrieved in first-in-first-out (FIFO) order. The first error returned is the first error that was stored. When you have read all errors from the queue, the ERROR annunciator turns off. The meter beeps once for each error generated.

• If more than 20 errors have occurred, the last error stored in the queue (the most recent error) is replaced with –350 “Queue Overflow”.

No additional errors are stored until you remove errors from the queue. If no errors have occurred and you read the error queue, the meter responds with +0, “No error”.

• The error queue is cleared when power has been off or after a *CLS (clear status) command has been executed.

• Front-panel operation: read the errors under the 3: ERROR

command in the SYStem menu.

ERROR annunciator is on, press Shift > (Menu Recall) to read

If the the errors stored in the queue. The errors are listed horizontally on the “parameter” level. The error queue is cleared when you go to the “parameter” level and then turn off the menu.

ERR 1: -113

First error in queue Error code

• Remote interface operation: use the following command to read the errors.

SYSTem:ERRor?

Errors have the following format (the error string may contain up to 80 characters).

–113, "Undefined header"

Chapter 3 Features and Functions

System-Related Operations

Self-Test

A power-on self-test occurs automatically when you turn on the multimeter. This limited test assures you that the meter is operational. This self-test does not perform the extensive set of tests that are included as part of the complete self-test described below.

A complete self-test runs a series of tests and takes approximately 15 seconds to execute. If all tests pass, you can have a high confidence that the meter is operational.

• The results of the complete self-test are stored in internal reading

memory (see page 50). Memory is cleared as the self-test stores this information. Other than clearing memory, the complete self-test does not alter the state of the meter.

• If the complete self-test is successful, “PASS” is displayed on the front

panel. If the self-test fails, “FAIL” is displayed and the annunciator turns on. See the HP 34420A Service Guide for instructions on returning the meter to Hewlett-Packard for service.

• Front Panel operation: You can perform some of the tests

individually or you can perform all tests together at once. Scroll through the parameters under the 4: TEST command in the SYStem menu.

ERROR

Another way to perform the complete self-test from the front panel is as follows: Hold down the meter; hold down the key for more than 5 seconds. The self-test will begin when you release the key.

• Remote operation: use the following command to initiate a self-test

and return the results:

*TST?

Returns “0” if the self-test is successful, or “1” if it fails.

Shift as you press the Power switch to turn on

Chapter 3 Features and Functions

System-Related Operations

Display Control

To speed up your measurement rate, or for security reasons, you may want to turn off the front-panel display. From the remote interface, you can also display a 11-character message on the front panel. See page 43

for information about the number of digits displayed.

• When the display is turned off, readings are not sent to the display and all display annunciators except ‘ERROR’ and ‘Shift’ are disabled. Front-panel operation is otherwise unaffected by turning off the display.

• The display state is stored in volatile memory; the display is enabled when power has been off or after a remote interface reset.

• You can display a message on the front panel by sending a command from the remote interface. The meter can display up to 11 characters of the message on the front panel; any additional characters are truncated. Commas, periods, and semicolons share a display space with the preceding character, and are not considered individual characters. When a message is displayed, readings are not sent to the display.

• Sending a message to the display from the remote interface overrides the display state; this means that you can display a message even if the display is turned off.

• Front-panel operation: set the display state under the 5: DISPLAY command in the SYStem menu.

The display always turns on for menu operation; this means that even when the display is turned off, you can still operate the menu.

• Remote operation: use the following commands to control the display:

DISPlay {OFF|ON} DISPlay:TEXT <

quoted string

disable/enab le t he d is play display the string

enclosed in quotes

DISPlay:TEXT:CLEar

clear the message in the display

The following statement shows how to display a message on the front panel from a Hewlett-Packard controller.

OUTPUT 722; "DISP:TEXT ’HELLO’"

Chapter 3 Features and Functions

System-Related Operations

Comma Separators

The meter can display readings on the front panel with or without a comma separator. This feature is available only from the front panel. See

“Menu Example 1” on page 35.

08.241,53 V 08.24153 V

With comma separator Without comma separator

(factory setting)

• The display format is stored in non-volatile memory, and does not

change when power has been off or after a remote interface reset. The comma separator is enabled when the meter is shipped from the factory.

• Front-panel operation: change the state of the comma display under the 9: COMMA command in the SYStem menu.

Firmware Revision Query

The meter has three microprocessors for control of various internal systems. You can query the meter to determine which revision of firmware is installed for each microprocessor.

• The meter returns three numbers. The first number is the firmware revision number for the measurement processor; the second is for the input/output processor; and the third is for the front-panel processor.

• Front-panel operation: read the revisions under the 11: REVISION command in the SYStem menu.

X.X-X.X-X.X

• Remote operation: use the following command to read the revision:

*IDN? returns “HEWLETT-PACKARD,34420A,0,X.X-X.X-X.X” Be sure to dimension a string variable with at least 40 characters.

Chapter 3 Features and Functions

System-Related Operations

SCPI Language Version

The meter complies with the rules and regulations of the present version

SCPI (Standard Commands for Programmable Instruments). You can

of determine the sending a command from the remote interface.

SCPI version with which the meter is in compliance by

You cannot query the

• The following command returns the

SCPI version from the front panel.

SCPI version.

SYSTem:VERSion?

Returns a string in the form “YYYY.V” where the “Y’s” represent the year of the version, and the “V” represents a version number for that year (for example, 1994.0).

Chapter 3 Features and Functions

Voltmeter Complete Terminal

The rear-panel VM Comp (voltmeter complete) terminal provides a low-true pulse after the completion of each measurement. Voltmeter complete and external trigger (see below) implement a standard hardware handshake sequence between measurement and switching devices.

Output

Approximately 2µs

External Trigger Terminal

You can trigger the meter by applying a low-true pulse to the rear-panel Ext Trig (external trigger) terminal. To use this terminal from the remote interface, you must select the external trigger source

(TRIGger:SOURce EXTernal).

Input

>1µs

You can use a simple switch to generate an external trigger using the Ext Trig input as shown below.

Chapter 3 Features and Functions

Chart Output (Analog Output)

You can use the Chart Output (Analog Output) connector on the rear panel to run a strip chart recorder or similar instrument. The connector provides an output voltage proportional to the measured voltage.

• The output can range from –3.00 V to +3.00 V.

• When chart output is disabled (Off), the output is set to 0 V.

• The output impedance is 1 kΩ.

• The output voltage is related to the input signal as follows:

(reading − chart null)

span

= chart output voltage

Note that reading includes the results of measurement unit conversion, filtering, null, and any math operation performed on the measurement.

• The chart output state (including the span and null values) is stored

in non-volatile memory.

• span cannot have a negative value.

• The chart output has a voltage "rollover" to prevent the loss of data,

see page 100.

Examples:

See page 38 for a menu procedure to enter a number.

1) To set the chart span so that a ±1 mV input signal produces a ±1.0 Volt chart output:

(0.001 − 0.0)

span

span =

0.001

1.00

= 1.00

= 0.001

When chart null is set to 0, the value

chart output = gain ∗ reading.

can be considered the gain and

span

Chapter 3 Features and Functions

Chart Output (Analog Output)

2) To set the chart output voltage to ±3.0 V to correspond to an input

temperature range of 5° C to 45° C with a mid temperature of 25° C (chart output is 0 V at 25° C).

(25 − chart null )

span

= 0 chart null = 25

and

(45 − 25)

span

= 3.0 span =

3.0

= 6.66

• Front Panel operation: Enable the chart output under the

5: CHART OUT command in the SYStem menu. Set the chart span under the 6: CHART SPAN command in the

SYStem menu. Set the chart offset under the 7: CHART NULL command in the

SYStem menu.

You can also press

Shift Null (Chart Null) to null the chart output

voltage based upon the displayed reading. This action places a null value in the Chart Offset register. Pressing

Shift > (Menu Recall)

will take you to the 7: CHART NULL command where you can manually edit the null value.

• Remote operation: use the following commands to enable and set the chart output values.

OUTPut {OFF|ON} OUTPut:REFerence

:OFFSet {<

number

>|MIN|MAX} :OFFSet:NULL :SPAN { <

number

>|MIN|MAX} :SPAN? :VALue {<

number

>|MIN|MAX} :GAIN?

Agilent 34420A Users Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

The Front-Panel at a Glance

The Front-Panel Menu at a Glance

Display Annunciators

The Rear Panel at a Glance

In This Book

Contents

To Prepare the Meter For Use

If the Meter Does Not Turn On

To Adjust the Carrying Handle

To Make Input Connections

Using the Cable Provided

Using a Custom Cable

To Measure Voltage

To Measure Resistance

To Measure Temperature With Thermistors

To Measure Temperature With RTDs

To Measure Temperature With Thermocouples

To Select a Range

To Set the Number of Digits

To Set the Integration Ti me

Front-Panel Display Formats

To Rack Mount the Meter

Front-Panel Menu Reference

A Front-Panel Menu Tutorial

Messages Displayed During Menu Use

Menu Example 1 The following steps show you how to turn on the menu, move up or down

Menu Example 2 The following exercise demonstrates how to use the menu recall feature

Menu Example 3 Some commands in the menu require that you enter a numeric

To Select an Input Channel

To Select a Range

To Set or Change the Number of Digits

To Set the Integration Ti me

To Make Null (Relative) Measurements

To Store Minimum and Maximum Readings (Stats )

To Trigger the Meter

To Use Reading Hold

To Make Voltage Ratio and Difference Measurements

To Use Reading Memory

General Measurement Configuration

Input Filters

Integration Time

Reducing Measurement Noise

Number of Digits Displayed

Ranging

Overload Detection

Voltage Measurement Configuration

Input Channels

Two Channel Measurements

Resistance Measurement Configuration

Offset Compensated Measurements

Low Power Measurements

Voltage Limited Measurements

Temperature Measurement Configuration

Measurement Units

RTD Measurements

Thermistor Measurements

Thermocouple Measurements

Math Operations

Scaling

Statistics

Null (Relative) Operation

Reading Hold

Triggering

Trigger Source Choices

Autotriggering In the autotrigger mode (front panel only), the meter continuously takes readings at the fastest rate possible for the present configuration. This is the power-on trigger source for front-panel operation.

Single Triggering In the single trigger mode (front panel only), you can manually trigger the meter by pressing reading, or the specified number of readings (sample count), each time you press the key. The

External Triggering In the external trigger mode, the meter will accept a hardware trigger applied to the Ext Trig terminal. The meter takes one reading, or the specified number of readings (sample count), each time Ext Trig receives a low-true pulse.

Internal Triggering In the internal trigger mode (remote interface only), the trigger signal is always present. When you place the meter in the wait-for-trigger state, the trigger is issued immediately. This is the power-on trigger source for remote interface operation.

Software (Bus) Triggering The bus trigger mode is available only from the remote interface. This mode is similar to the single trigger mode from the front panel, but you trigger the meter by sending a bus trigger command.

The Wait-for-Trigger State

Halting a Measurement in Progress

Number of Samples

Number of Triggers

Trigger Delay

Automatic Trigger Delays

System-Related Operations