Agilent Technologies 34420A User manual

The34420A is a 71/2digit,high performancenanovolt,micro-ohm
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
HP34420A
Nano Volt/Micro Ohm Meter
Agilent 34420A
GPIB

The Front-Panel at a Glance
1Input channel select 5Menu operation keys
2Measurement function keys 6Range/number of digits displayed keys
3Math operation keys 7Single trigger/autotrigger/auto hold key
4Filter select key 8Shift / local key
2

The Front-Panel Menu at a Glance
The menu is organized in a top-down tree structure with three levels.
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 Ø
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] Ø
[5: INJECTED I] Ø 6: CAL COUNT Ø 7: MESSAGE
NOTE: The commands enclosed in square brackets ([ ]) in the CAL MENU are "hidden" unless the meter is UNSECURED for calibration.
To turn on menu press:
To move left/right To move up/down
To enter a command press:
3

Display Annunciators
*Turns on during a measurement.
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 indicating the difference between inputs on channel 1 and channel 2.
Ch1 / Ch2 Meter is indicating the ratio of the inputs on channel 1 and channel 2.
ΩMeter 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 limited 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.
To review the display annunciators, hold down the Shift key as you
turn on the meter.
4

The Rear Panel at a Glance
1Chassis ground 5Voltmeter complete output terminal
2Power-line fuse-holder assembly 6External trigger input terminal
3Power-line voltage setting7GPIB (IEEE-488) interface connector
4Chart recorder output terminal
(Analog out)
8RS-232 interface connector
Use the front-panel Input / Output Menu to:
•Select the GPIB or RS-232 interface
•Set the GPIB bus address
•Set the RS-232 baud rate and parity
5

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
6
Agilent Technologies Sales Office.

Contents
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
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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 (RS-232) 103
Parity Selection (RS-232) 104
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
Chapter 4 Remote Interface Reference
Command Summary 117
Simplified Programming Sequence 126
Using the MEASure? Command 128
Using the CONFigure Command 128
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
Contents
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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 (SRQ) and Serial POLL 162
Using *STB? to Read the Status Byte 163
To Interrupt Your Bus Controller Using SRQ 163
To Determine When a Command Sequence is Completed 163
How to Use the Message Available Bit (MAV) 164
Using *OPC to Signal When Data is in the Output Buffer 164
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
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Chapter 5 Error Messages
Execution Errors 201
Self-Test Errors 208
Calibration Errors 210
Chapter 6 ApplicationPrograms
HP BASIC Language Programs 215
HPBASIC / HP-IB ProgramExample1215
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
Contents
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1
Quick Start

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 Shift (the Shift display
annunciator will turn on). Then, press the key that has the desired label
above it. For example, to select the temperature measurement function,
press Shift DCV .
If you accidentally press Shift , just press it again to turn off the Shift
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.
12

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
in 61/2digit resolution, channel 1 input, and digital filter on.
To view the display with all annunciators turned on,
hold down Shift as you turn on the meter.
3Performacomplete self-test.
The complete self-test performs a more extensive series of tests than
those performed at power-on. Hold down Shift as you press the
power switch to turn on the meter; continue to hold Shift for more than
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.
1
Chapter 1 Quick Start
To Prepare the Meter For Use
13
Agilent Technologies Sales Office.
GPIB
Agilent for service.

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 250mAT 250 V fuse,order partnumber 2110-0817.
This fuse is used for all power line voltage settings.
Chapter 1 Quick Start
If the Meter Does Not Turn On
14
Agilent for service.

1 Remove the power cord. Remove
the fuse holder assembly from the rear 2 Install the fuse. Remove the line-voltage selector from the assembly.
250 mAT fuse
(250V)
3Rotate the line-voltage selector until
the correct voltage appears in the window.
100, 120, 220 (230), or 240 Vac
4Replace the fuse-holder assembly in the
rear panel.
Install the correct fuse and verify that the correct line voltage appears in the window.
1
Chapter 1 Quick Start
If the Meter Does Not Turn On
15

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 Adjust the Carrying Handle
16

To Make Input Connections
Using the Cable Provided
Align the front panel connector and cable conductors, press in.
Tighten coupling nut.
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.
Warning
The connector body and cable shield are connected to earth ground.
RED HI
CH1 BLACK LO
HI
CH2 GREEN
WHITE
LO
Torque to 20 in-lb
maximum
1
Chapter 1 Quick Start
To Make Input Connections
17
Agilent Technologies.

Using a Custom Cable
Refer to page 272 for additional information about building custom input
cables.
Channel 1
HI LO
DCV + –
4-WireΩSource + Source –
2-WireΩSource and Sense + Source and Sense –
Thermistor Source and Sense + Source and Sense –
Channel 2
HI LO
DCV + –
4-WireΩSense + Sense –
Thermocouple + –
Earth Ground (shell)
Chapter 1 Quick Start
To Make Input Connections
18