User’s Guide
Part Number 34420-90001
December 1994
For Safety information, Warranties, and Regulatory information,
see the pages behind the Index.
© Copyright Hewlett-Packard Company 1994
All Rights Reserved.
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
1
digit, high performance nanovolt, micro-ohm
/
2
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
2
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
Ø
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.
Ø
3
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.
4
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
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
Hewlett-Packard Sales Office.
6
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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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
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
8
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
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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
10
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
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
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
12
Chapter 1 Quick Start
To Prepare the Meter For Use
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
1
digit resolution, channel 1 input, and digital filter on.
in 6
/
2
1
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
13
Chapter 1 Quick Start
If the Meter Does Not Turn On
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.
14
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.
1
100, 120, 220 (230), or 240 Vac
Install the correct fuse and verify that the correct line voltage appears in the window.
15
Chapter 1 Quick Start
To Adjust the Carrying Handle
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
16
Carrying Position
Chapter 1 Quick Start
To Make Input Connections
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
1
RED HI
HI
WHITE
LO
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.
17
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.
18
Chapter 1 Quick Start
To Measure Voltage
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
1
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.
19
Chapter 1 Quick Start
To Measure Resistance
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
OR
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).
20
2-WIRE
Chapter 1 Quick Start
To Measure Temperature With Thermistors
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
R
0
1
OPEN
RED
(SOURCE)
CH1 GREEN
CH2
(SENSE) WHITE
BLACK
21
Chapter 1 Quick Start
To Measure Temperature With Thermocouples
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
OR
INTERNAL
CH1 BLACK THERMISTOR
GREEN
CH2
RED
CH1 OPEN
BLACK
GREEN
CH2
WHITE
WHITE
OR
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).
22
Chapter 1 Quick Start
To Select a Range
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
1
• 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.
23
Chapter 1 Quick Start
To Set the Number of Digits
To Set the Number of Digits
1
1
You can set the display to show 4
⁄
, 5
2
1
⁄
, 6
⁄
2
2
book, the most significant digit (leftmost on the display) is referred to as
1
⁄
the “
” digit, since it can only be a “0” or “1”. The number of digits
2
displayed also depends upon the integration time set, see page 25.
, or 7
1
⁄
digits. In this
2
Press the Shift key
1
Selects 5
(1 PLC)
⁄2 digits
• The number of digits is set to 6
Selects 7
(100 PLC)
Selects 6
(10 PLC)
1
⁄2 digits
1
⁄
digits at power-on and after a
2
1
⁄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
24
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
10
20
100
200
Filter Off
Max Digits Shown
41⁄2 5
51⁄2 6
61⁄2 7
61⁄2 7
1
⁄2 7
6
71⁄2 7
71⁄2 7
71⁄2 7
Filter On
Max Digits Shown
1
⁄2
1
⁄2
1
⁄2
1
⁄2
1
⁄2
1
⁄2
1
⁄2
1
⁄2
1
• You can always show fewer digits than the maximum allowed
1
⁄
(the minimum number of digits shown is 4
).
2
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.
25
6 digits
Chapter 1 Quick Start
Front-Panel Display Formats
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,
1
⁄2 digits are displayed.
6
1
⁄2 digits are displayed.
5
1
⁄2 digits are displayed.
7
O.VLD mV
This is an overload indication on the 1 mV range.
26
Chapter 1 Quick Start
To Rack Mount the Meter
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.
1
To remove the rubber bumper, stretch a corner and then slide it off.
27
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).
28
2
Front-Panel Operation
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