HP 34970a schematic

Service Gu ide

Publication Number 34970-90012 (order as 34970-90101 manual set) Edition 3, March 2003

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

Note: The schematics for the 34970A are available as a separate downloadable PDF file from the Agilent web site at www.agilent. com.

Agilent 34970A Data Acquistion / S witch Unit

Note: Unless otherwise indicated, this manual applies to all serial numbers.

The Agilent Technologies 34970A combines precision measurement capability with flexible signal connections for your production and development test systems. Three module slots are built into the rear of the instrument to accept any combination of data acquisition or switching modules. The combination of data logging and data acquisition features makes this instrument a versatile solution for your testing requirements now and in the future.

Convenient Data Logging Features

• Direct measurement of thermocouples, RTDs, thermistors, dc voltage,

ac voltage, resistance, dc current, ac current, frequency, and period

• Interval scanning with storage of up to 50,000 time-stamped readings

• Independent channel configuration with function, Mx+B scaling,

and alarm limits available on a per-channel basis

• Intuitive user interface with knob for quick channel selection,

menu navigation, and data entry from the front panel

• Portable, ruggedized case with non-skid feet

• BenchLink Data Logger Software for Microsoft

®

Windows

®

included

Warning

Flexible Data Acquisition / Sw itching Features

1

• 6

⁄

-digit multimeter accuracy, stability, and noise rejection

2

• Up to 60 channels per instrument (120 single-ended channels)

• Reading rates up to 600 readings per second on a single channel and

scan rates up to 250 channels per second

• Choice of multiplexing, matrix, general-purpose Form C switching,

RF switching, digital I/O, totalize, and 16-bit analog output functions

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

• SCPI (Standard Commands for Programmable Instruments) compatib ility

The procedures in this manual are intended for use by qualified, service-trained personnel only.

Agilent 34970A Data Acquisition / S witch Unit

The Front Panel at a Glance

Denotes a menu key. S e e th e n ex t p a g e f or d et a il s on me nu o pe ra tio n .

1 State Storage / Remote Interface Menus

2 Scan Start / Stop Key 3 Measurement Configuration Menu 4 Scaling Configuration Menu 5 Alarm / Alarm Output Configuration Menu 6 Scan-to-Scan Interval Menu 7 Scan List Single Step/Read Key

8 Advanced Measurement / Utility Menus 9 Low-Level Module Contr ol Keys 10 Single-Channel Monitor On/Off Key 11 View Scanned Data, Alarms, Errors Menu 12 Shift / Local Key 13 Knob 14 Navigation Arrow Keys

2

The Front-Panel Menus at a Glance

Several of the front-panel keys guide you through menus to configure various parameters of the instrument (see previous page). The following steps demonstrate the menu structure using the key.

1 Press the menu key. You are automatically guided to the first level of the menu. Rotate the knob to view the other choices on the first level of the menu.

The menu will automatically timeout after about 20 seconds of inactivity. You will be returned to the operation in progress prior to entering the menu.

2 Press the same menu key again to move to the next item of the menu. Typically, this is where you choose parameter values for the selected operation.

3 Rotate the knob to view the choices on this level of the menu. When you reach the end of the list, rotate the knob in the opposite direction to view all of the other choices.

The current selection is highlighted for emphasis. All other choices are dimmed.

4 Press the same menu key again to accept the change and exit the menu. A brief confirmation message is displayed.

Tip: To review the current configuration of a specific menu, press the menu key several times. A message

NO CHANGES is displayed when you exit the menu.

3

Display Annunciators

SCAN MON VIEW CONFIG

ADRS RMT ERROR EXT ONCE MEM LAST MIN MAX SHIFT 4W OC

Scan is in progress or enabled. Press and hold again to t urn of f . Monitor mode is enabled. Press again to turn off. Scanned readings, alarms, errors, or relay cycles are being viewed. Channel configuration is in progress on displayed channel. Measurement is in progress. Instrument is addressed to listen or talk over the remote interface. Instrument is in remote mode (remote interface). Hardware or remote interface errors are detected. Press to read err o r s . Instrument is configured for an external scan interval. Scan Once mode is enabled. Press t o initiat e and hold key to disable. Reading memory overflow; new readings will overwrite the oldest readings. Viewed data is the last reading stored during most recent scan. Viewed data is the minimum reading stored during most recent scan. Viewed data is the maximum reading stored during most recent scan.

has been pressed. Press again to turn off. 4-wire function is in use on displayed channel. Offset compensation is enabled on displayed channel. Alarms are enabled on displayed channel. Mx+B scaling is enabled on displayed channel. HI or LO alarm condition has occurred on indicated alarms.

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

4

The Rear Panel at a Glance

WARNING

1 Slot Identifier (100, 200, 300)

2 Ext Trig Input / Alarm Outputs / Channel

Advance Input / Channel Closed Output (for pinouts, see chapter 4 in User’s Guide)

3 RS-232 Interface Connector

Use the Menu to:

• Select the GPIB or RS-232 interface (see chapter 2 in User’s Guide).

• Set the GPIB address (see chapter 2 in User’s Guide).

• Set the RS-232 baud rate, parity, and flow control mode (see chapter 2 in User’s Guide).

4 Power-Line Fuse-Holder Assembly 5 Power-Line Voltage Setting 6 Chassis Ground 7 GPIB (IEEE-488) Interface Connector

For protection from electrical shock, the power cord ground must not be defeated. If only a two-contact electrical outlet is available, connect the instrument’s chassis ground screw (see above) to a good earth ground.

5

The Plug-In Modules at a Glance

For complete specifications on each plug-in module, refer to the module sections in chapter 1.

34901A 20-Channel Armature Multiplexer

• 20 channels of 300 V switching

• Two channels for DC or AC current measurements (100 nA to 1 A)

• Built-in ther mocouple reference junction

• Switching speed of up to 60 channels per second

• Connects to the internal multimeter

Each of the 20 channels switches both fully isolated inputs to the internal multimeter. The module is divided into two banks of 10 two-wire channels each. When making four-wire resistance measurements, channels from Bank A are automatically paired with channels from Bank B. Two additional fused channels are included on the module (22 channels total) for making calibrated

AC current measurements with the internal multimeter (external shunt

resistors are not required). You can close multiple channels on this module only if you have not configured any channels to be part of the scan list. Otherwise, all channels on the module are break-before-make.

HI and LO inputs, thus providing

DC or

34902A 16-Channel Reed Multiplexer

• 16 channels of 300 V switching

• Built-in ther mocouple reference junction

• Switching speed of up to 250 channels per second

• Connects to the internal multimeter

Use this module for high-speed scanning and high-throughput automated test applications. Each of the 16 channels switches both

HI and LO inputs, thus providing fully isolated inputs to the internal

multimeter. The module is divided into two banks of eight two-wire channels each. When making four-wire resistance measurements, channels from Bank A are automatically paired with channels from Bank B. You can close multiple channels on this module only if you have not configured any channels to be part of the scan list. Other wise, al l channels on the module are break-before-make.

6

34903A 20-Channel Actuator / G eneral-Purpose Switch

• 300 V, 2 A actuation and switching

• SPDT (Form C) latching relays

• Breadboard area for custom circuits

Use this module for those applications that require high-integrity contacts or quality connections of non-multiplexed signals. This module can switch 300 V, 1 A (50 W maximum switch power) to your device under test or to actuate external devices. Screw terminals on the module provide access to the Normally-Open, Normally-Closed, and Common contacts for each of the 20 switches. A breadboard area is provided near the screw terminals to implement custom circuitry, such as simple filters, snubbers, or voltage dividers.

34904A 4x8 Two-Wire Matrix Switch

• 32 two-wire crosspoint s

• Any combination of inputs and outputs can be connected at a time

• 300 V, 1 A switching

Use this module to connect multiple instruments to multiple points on your device under test at the same time. You can connect rows and columns between multiple modules to build larger matrices such as 8x8 and 4x16, with up to 96 crosspoints in a single mainframe.

34905/6A Dual 4-Channel RF Multiplexers

• 34905A (50Ω ) / 34906A (75Ω )

• 2 GHz bandwidth with on-board SMB connections

• 1 GHz bandwidth with SMB-to-BNC adapter cables provided

These modules offer wideband switching capabilities for high frequency and pulsed signals. Each module is organized in two independent banks of 4-to-1 multiplexers. Both modules offer low crosstalk and excellent insertion loss performance. To create larger cascade multiple banks together. Only one channel in each bank may be closed at a time.

RF multiplexers, you can

7

34907A Multifunction Module

• Two 8-bit Digital Input/Output ports, 400 mA sink, 42 V open collector

• 100 kHz Totalize input with 28 bits of resolution

• Two 16-bit, ± 12 V Calibrated Analog Outputs

Use this module to sense status and control external devices such as solenoids, power relays, and microwave switches. For greater flexibility, you can read digital inputs and the count on the totalizer during a scan.

34908A 40-Channel Single-Ended Multiplexer

• 40 channels of 300 V single-ended (common LO) switching

• Built-in thermocouple isothermal reference junction

• Switching speed of up to 60 channels per second

• Connects to the internal multimeter

Use this module for high-density switching applications which require single-wire inputs with a common to ensure that only one relay is connected at any time.

LO. All relays are break-before-make

8

In This Book

Specifications Chapter 1 lists the technical specifications for the mainframe and plug-in modules.

Quick Start Chapter 2 helps you get familiar with a few of the instrument’s front-panel features.

Front-Panel Overview Chapter 3 introduces you to the front-panel menus and describes some of the instrument’s menu features.

Calibration Procedures Chapter 4 provides calibration, verification, and adjustment procedures for the instrument.

Theory of Operation Chapter 5 describes block and circuit level theory related to the operation the instrument.

Service Chapter 6 provides guidelines for returning your instrument to Agilent Technologies for servicing, or for servicing it yourself.

Replaceable Parts Chapter 7 contains detailed parts lists for the mainframe and plug-in modules.

Schematics Chapter 8 contains the instrument’s block diagram, schematics, disassembly drawings, and component locator drawings.

If you have questions relating to the operation of the 34970A, call 1-800-452-4844 in the United States, or contact your nearest Agilent Technologies Sales Office.

If your 34970A fails within three years of original purchase, Agilent will repair or replace it free of charge. Call 1-877-447-7278 and ask for “Express Exchange.”

9

Contents

Chapter 1 Specifications

DC, Resistance, and Temperature Accuracy Specifications 16 DC Measurement and Operating Characteristics 17 AC Accuracy Specifications 18 AC Measurement and Operating Characteristics 19 Measurement Rate s an d Sys t em Char a c ter i sti c s 20 Module Specifications 21 BenchLink Data Logger Soft ware Specifications 24 Product and Module Dimensions 25 To Calculate Total Measurement Error 26 Interpreting Internal DMM Specifications 28 Configuring for Highest Accuracy Measurements 31

Chapter 2 Quick Start

To Prepare the Instrument for Use 35 To Connect Wiring to a Module 36 To Set the Time and Date 38 To Configure a Measurement Channel 39 To Monitor a Single Ch an ne l 40 To Close a Channel 41 If the Instrument Does Not Turn On 42 To Adjust the Carrying Handle 44 To Rack Mount the Instrument 45

Chapter 3 Front-Panel Overview

Front-Panel Menu Reference 49 To Unsecure for Calibration 51 To Secure Against Cali br a tio n 51 To Change the Security Code 52 Error Messages 52 To Perform a Zero Adjustment 53 To Apply Mx+B Scaling to Measurements 54 To Read the Relay Cycle Count 55 To Read a Digital Input Port 56 To Write to a Digital Output Port 57 To Read the Totalizer Count 58 To Output a DC Voltage 59

10

Contents

Chapter 4 Calibration Procedures

Agilent Technologies Calibration Services 63 Calibration Interval 63 Adjustment is Recommended 63 Time Required for Calibration 64 Automating Calibration Procedures 64 Recommended Test Equipment 65 Input Connections 66 Calibration Security 67 To Unsecure the Instrument Without the Security Code 68 Calibration Message 69 Calibration C o unt 69 Calibration Pr ocedure 70 Aborting a Calibration in Progress 70 Test Considerations 71 Performance Verification Tests 72 Self-Test 73 Quick Performanc e Check 74 Performance Verification Tests 74 Internal DMM Verification Tests 75 Zero Offset Verification 75 Gain Verification 77 Optional AC Performance Verification Tests 80 Internal DMM Adj ustments 81 Zero Adjustment 81 Gain Adjustment 82 –10 Vdc Adjustment Pro cedure (Optional) 85 Plug-in Mo dule Test Consideration s 87 Relay Verification 88 Relay Cycle Count 88 34901A Relay Contact Resistan ce V eri fication (Optional) 89 34902A Relay Contact Resistan ce V eri fication (Optional) 96 34903A Relay Contact Resistan ce V eri fication (Optional) 101 34904A Relay Contact Resistan ce V eri fication (Optional) 102 34905A/06A Relay Contact Resistance Verification (Optional) 105 34908A Relay Contact Resistan ce V eri fication (Optional) 106 Thermocouple Reference Junction (Optional) 112 Thermocouple Reference Junction Verificati on 112 Thermocouple Reference Junction Adjustments 113 34907A Analog Ou tput 114 Analog Output Verification Test 114 Analog Output Adjustment 115

Contents

11

Contents

Chapter 5 Theory of Operation

System Block Diagram 119 Floating Logic 120 Memory 123 Earth-Referenced Logic 124 Power Supplies 125 Front Panel 127 Backplane 128 Analog Bus 128 Digital Bus 128 Internal DMM 129 DMM Block Diagram 129 Input 130 Input Amplifier 131 Ohms Current Source 133 AC Circuit 134 A-to-D Converter 136 Switch Modules 138 Switch Module Control 138 Relay Drivers 140 34901A 142 34902A 144 34903A 146 34904A 147 34905A/34906A 148 34908A 149 Multifunction Mo d ul e 151 Multifunction Control 151 Totalizer 153 Analog Output 154 Digital I/O 155

Chapter 6 Service

Operating Checklist 159 Is the instrument inope rat i v e? 159 Does the instrument fail self-test? 159 Is the Current measurement function inoperative? 159 Types of Service Available 160 Standard Repair Service (worldwide) 160 Express Exchange (U.S.A. only) 160 Repackaging for Shipment 161 Cleaning 161 Electrostatic Discharge (ESD) Precautions 162 Surface Mount Repair 162 To Replace the Power-Line Fuse 163

12

Contents

Chapter 6 Service (continued)

Troubleshoot i ng Hi nt s 163 Unit is Inoperative 163 Unit Reports Error 705 164 Isolating to an Assembly 164 Unit Fails Self-Test 164 Power Supplies 165 Self-Test Procedures 167 Power-On Self-Test 167 Complete Self-Test 167 Plug-in Module Self-Test 167 Self-Tests 168 Battery Check and Replacement 172 To Verify the Battery 173 To Replace the Battery 173 Disassembly 174 General Disassembly 175 Internal DMM Disassembly 176 Front-Panel Chassis Disassembly 177 Additional Disassembly 178 Plug-in Module Disassembly 179

Chapter 7 Replaceable Parts

Replaceable Parts 182 To Order Replaceable Parts 182 34970A Mainframe 183 34970-66501 Main PC Assembly (A1) 184 34970-66502 Front-Panel and Keyboard PC Asse mb ly (A2) 189 34970-66503 Backplane PC Assemb ly (A 3) 190 34970-66504 Internal DMM PC Assembly (A4) 191 34901A 20-Channel Multiplexer 196 34902A 16-Channel Multiplexer 200 34903A 20-Channel Actuator 202 34904A 4x8 Matrix 204 34905A/34906A RF Multiplexer 207 34907A Multifunction Modul e 209 34908A 40-Channel Multiplexer 213 Manufacturer’s List 216

Contents

13

Contents

Chapter 8 Schematics

Agilent 34970A System Block Diagram 221 A1 Component Locator (top) 222 A1 Component Locator (bottom) 223 A1 Power Supply Schematic (Sheet 1 of 4) 224 A1 Floating Logic Schematic (Sheet 2 of 4) 225 A1 Earth Referenced Logic Schematic (Sheet 3 of 4) 226 A1 Memory Schematic (Sheet 4 of 4) 227 A2 Component Locator 228 A2 Display and Keyboard Schematic 229 A3 Component Locator 230 A3 Backplane Schematic 231 A4 Component Locator (top) 232 A4 Component Locator (bottom) 233 A4 Input and Protection Schematic (Sheet 1 of 4) 234 A4 Input Amplifier and Ohms Cu rr en t Sch em ati c (Sheet 2 of 4) 235 A4 AC Schematic (Sheet 3 of 4) 236 A4 A/D Converter Schematic (Sheet 4 of 4) 237 34901A 20-Channel M ul tipl exe r Compo ne nt Loc a t or 238 34901A 20-Channel Multiplexer Schematic (Sheet 1 of 5) 239 34901A 20-Channel Multiplexer Schematic (Sheet 2 of 5) 240 34901A 20-Channel Multiplexer Schematic (Sheet 3 of 5) 241 34901A 20-Channel Multiplexer Schematic (Sheet 4 of 5) 242 34901A 20-Channel Multiplexer Schematic (Sheet 5 of 5) 243 34902A 16-Channel M ul tipl exe r Compo ne nt Loc a t or 244 34902A 16-Channel Multiplexer Schematic (Sheet 1 of 4) 245 34902A 16-Channel Multiplexer Schematic (Sheet 2 of 4) 246 34902A 16-Channel Multiplexer Schematic (Sheet 3 of 4) 247 34902A 16-Channel Multiplexer Schematic (Sheet 4 of 4) 248 34903A 20-Chann el Actu at o r Compo ne nt Locator 249 34903A 20-Channel Actuator Schematic (Sheet 1 of 3) 250 34903A 20-Channel Actuator Schematic (Sheet 2 of 3) 251 34903A 20-Channel Actuator Schematic (Sheet 3 of 3) 252 34904A 4x8 Matri x Compo ne nt Loc a tor 253 34904A 4x8 Matrix Schematic (Sheet 1 of 3) 254 34904A 4x8 Matrix Schematic (Sheet 2 of 3) 255 34904A 4x8 Matrix Schematic (Sheet 3 of 3) 256 34905A/34906A R F Mul t ipl exe r Co mpone nt Loc a tor 257 34905A/34906A RF Multiplexer Schematic (Sheet 1 of 2) 258 34905A/34906A RF Multiplexer Schematic (Sheet 2 of 2) 259 34907A Multifun c tio n Mo dul e Com p on en t Locato r 260 34907A Multifunction Modul e Sc hema t ic (S he et 1 of 5) 261 34907A Multifunction Modul e Sc hema t ic (S he et 2 of 5) 262 34907A Multifunction Modul e Sc hema t ic (S he et 3 of 5) 263 34907A Multifunction Modul e Sc hema t ic (S he et 4 of 5) 264 34907A Multifunction Modul e Sc hema t ic (S he et 5 of 5) 265 34908A 40-Channel M ul tipl exe r Compo ne nt Loc a t or 266 34908A 40-Channel Multiplexer Schematic (Sheet 1 of 3) 267 34908A 40-Channel Multiplexer Schematic (Sheet 2 of 3) 268 34908A 40-Channel Multiplexer Schematic (Sheet 3 of 3) 269

14

1

• DC, Resistance, and Temperature Accuracy Specifications, on page 16

• DC Measurement and Operating Characteristics, on page 17

• AC Accuracy Specifications, on page 18

• AC Measurement and Operating Characteristics, on page 19

• Measurement Rates and System Characteristics, on page 20

• Module Specifications:

34901A, 34902A, 34908A, 34903A, 34904A, on page 21 34905A, 34906A, on page 22 Typical AC Performance Graphs, on page 23 34907A, on page 24

• BenchLink Data Logger Software Specifications, on page 24

• Product and Module Dimensions, on page 25

• To Calculate Total Measurement Error, on page 26

• Interpreting Multimeter Specifications, on page 28

• Configuring for Highest Accuracy Measurements, on page 31

1

Specifications

Chapter 1 Specifications

DC, Resistance, and Temperature Accuracy Specifications

DC, Resistance, and Temperature Accura cy Specifications

± ( % of reading + % of range )

[1]

Includes measurement error, switching error, and transducer conversion error

Function Range

[3]

Test Current or Burden Voltage

DC Voltage 100.0000 mV

1.000000 V

10.00000 V

100.0000 V

300.000 V

Resistance

DC Current

34901A Only

Temperature Thermocouple

RTD R

[4]

[6]

100.0000 Ω

1.000000 kΩ

10.00000 kΩ

100.0000 kΩ

1.000000 MΩ

10.00000 MΩ

100.0000 MΩ

10.00000 mA

100.0000 mA

1.000000 A Type

B E

J

K N R S T

from 49Ω

0

to 2.1 kΩ

1 mA current source 1 mA 100 10

µA

5 500 nA 500 nA || 10 M

< 0.1 V burden < 0.6 V < 2 V

1100

-150

-100

-100 300 400

-100

-200°C to 600°C 0.06°C0.003°C

Thermistor 2.2 k, 5 k, 10 k -80

µA

Ω

Best Range Accuracy

°C to 1820°C °C to 1000°C

°C to 1200°C

°C to 1300°C °C to 1760°C °C to 1760°C

°C to 400°C

°C to 150°C 0.08°C0.002°C

[2]

24 Hour

23 °C ± 1 °C

0.0030 + 0.0035

0.0020 + 0.0006

0.0015 + 0.0004

0.0020 + 0.0006

0.0020 + 0.0020

0.0030 + 0.0035

0.0020 + 0.0006

0.0020 + 0.0005

0.002 + 0.00 1

0.015 + 0.00 1

0.300 + 0.01 0

0.005 + 0.010

0.010 + 0.004

0.050 + 0.006

[5]

1.2

°C

1.0

°C °C

1.0

°C

1.0

°C °C

1.2

°C

1.0

°C

90 Day

23 °C

± 5 °C

0.0040 + 0.0040

0.0030 + 0.0 00 7

0.0020 + 0.0 00 5

0.0035 + 0.0 00 6

0.0035 + 0.0 03 0

0.008 + 0.004

0.008 + 0.001

0.020 + 0.001

0.800 + 0.010

0.030 + 0.020

0.030 + 0.005

0.080 + 0.010

23 °C

0.0050 + 0.0040

0.0040 + 0.0 00 7

0.0035 + 0.0 00 5

0.0045 + 0.0 00 6

0.0045 + 0.0 03 0

0.010 + 0.004

0.010 + 0.001

0.040 + 0.001

0.800 + 0.010

0.050 + 0.020

0.050 + 0.005

0.100 + 0.010

Extended Range Accuracy

400

°C to 1100°C

-200

°C to -150°C

-210

-200

°C to -100°C

-200

°C to -100°C °C to 300°C

-50

°C to 400°C

-200

°C to -100°C

1 Year

± 5 °C

1.8

°C

1.5

°C °C

1.2

1.5

°C

1.5

°C °C

1.8

°C

1.5

°C

[5]

Temperature

Coefficient /°C

0 °C – 18 °C 28 °C – 55 °C

0.0005 + 0.0005

0.0005 + 0.0001

0.0005 + 0.0003

0.0006 + 0.0005

0.0006 + 0.0001

0.0010 + 0.0002

0.0030 + 0.0004

0.1500 + 0.0002

0.002 + 0.0020

0.002 + 0.0005

0.005 + 0.0010

0.03

°C

0.03

°C °C

0.03

°C

0.03

°C °C

0.03

°C

0.03

°C

1

⁄

[1] Specifications are for 1 hour warm up and 6 [2] Relative to calibration standards

digits

2

[3] 20% over range on all ranges except 300 Vdc and 1 Adc range s [4] Specifications are for 4-wire ohms function or 2-wire ohms using Scaling to remove the offset. Without Scaling, add 4

Ω additional error in 2-wire ohms function.

[5] 1 year acc uracy. For total measurement accuracy, add tempe r ature probe error. [6] Thermocouple specifications not guaranteed when 34907A module is present

16

Chapter 1 Specifications

DC Measurement and Operating Characteristics

1

DC Measurement Characteristics

[1]

DC Voltage

Measurement Method:

Continuously Integrating, Multi-slope III A/D Converter

A/D Linearity :

0.00 02 % of reading + 0. 00 01 % of range Input Resistance: 100 mV, 1 V, 10 V ranges 100 V, 300 V ranges Input Bias Current: Input Protection:

Selectable 10 M

Ω or >10 GΩ

10 MΩ ±1% < 30 pA at 25

°C

300 V on all ranges

Resistance

Measurement Method: Offset Compensation:

Max. Lead Resistance: Input Protection:

Selectable 4-wi re or 2- wire O hms, Current source reference to LO input Selectable on 100

Ω, 1 kΩ, 10 kΩ ranges

10% of range per lead for 100 1 k

Ω ranges. 1 kΩ on all other range s

300 V on all ranges

DC Current

Shunt Resistance: Input Protection:

5

Ω for 10 mA, 100 mA; 0.1Ω for 1A.

1.5A 250 V fuse on 34901A module

Thermocouple

Conversion: Reference Junction Type: Open T/C Check:

ITS-90 software compensation Internal, Fixed, or External Selectable per channel. Open > 5 k

RTD α = 0.00385 (DIN ) and 0 . 00 391 Thermistor 44004, 44007, 44006 series Measurement Noise Rejection 60 Hz (5 0 Hz)

DC CMRR:

Integration Time

200 PLC / 3.33s (4s) 100 PLC / 1.67s (2s) 20 PLC / 333 ms (400 ms) 10 PLC / 167 ms (200 ms) 2 PLC / 33.3 ms (40 ms) 1 PLC / 16.7 ms (20 ms) < 1 PLC

140 dB Normal Mode Rejection

[4]

110 dB

[4]

105 dB

[4]

100 dB

[4]

95 dB 90 dB 60 dB 0 dB

[2]

[3]

Ω and

DC Operating Characteristics

[6]

Function

DCV, DCI, and Resistance:

Single Channel Measurement Rates Function

DCV, 2-Wire Ohms:

Thermocouple:

Digits

1

6

⁄

2

1

6

⁄

2

1

5

⁄

2

1

5

⁄

2

1

4

⁄

2

Resolution

1

6

⁄

(10 PLC)

2

1

5

⁄

(1 PLC)

2

1

⁄

(0.02 PLC)

4

2

0.1

°C (1 PLC)

[5]

Readings/s

0.6 (0.5) 6 (5)

60 (50)

300 600

[8]

Additional Noise Error

0% of range 0% of range

0.001% of range

0.01% of range

(0.02 PLC)

0.01

RTD, Thermistor:

0.1

°C (0.02 PLC)

1

°C (10 PLC)

°C (1 PLC)

Autozero OFF Operation

Following instrument warm-up at calibration temperature and < 10 minutes, add 0.0002% range additional error + 5

Ω

Settling Considerations

Reading settling times are affected by source impedance, low dielectric absorption characteristics, and input signal changes.

[1] 300 Vdc isolation voltage (ch-ch, c h-earth) [2] For 1 k [3] For power line frequency [4] For power line frequency For power line frequency [5] Reading speeds for 60 Hz and (50 Hz) operation; autozero OFF [6] 6 [7] Add 20

Ω unbalance in LO lead

1

⁄

digits=22 bits, 5

2

µV for DCV, 4 µA for DCI, or 20 mΩ for resistance

±0.1% ±1%, use 80 dB. ±3%, use 60 dB .

1

⁄

digits=18 bits, 4

2

1

⁄

digits=15 bits

2

[8] For fixed function and range, readings to memory, scaling and alarms off, autozero OFF

[7]

Readings/s

6 (5)

57 (47)

600

57 (47)

220

6 (5)

57 (47)

220

±1 °C

µV.

17

Chapter 1 Specifications

AC Accuracy Specifications

± ( % of reading + % of range )

[1]

Includes measurement error, switching error, and transducer conversion error

Function Range

[3]

Frequency

24 Hour

[2]

23 °C ± 1 °C

90 Day

23 °C

± 5 °C

1 Year

23 °C

± 5 °C

Temperature

Coefficient /°C

0 °C – 18 °C 28 °C – 55 °C

True RMS AC Voltage

Frequency and Period

True RMS AC Current

34901A Only

100.0000 mV

[4]

to 100 V

300.0000 V 3 Hz – 5 Hz

[6]

100 mV

to

300 V

10.00000 mA and

1.000000 A

100.0000 mA

3 Hz – 5 Hz 5 Hz – 10 Hz 10 Hz – 20 kHz 20 kHz – 50 kHz 50 kHz – 100 kHz 100 kHz – 300 kHz

5 Hz – 10 Hz 10 Hz – 20 kHz 20 kHz – 50 kHz 50 kHz – 100 kHz 100 kHz – 300 kHz

3 Hz – 5 Hz 5 Hz – 10 Hz 10 Hz – 40 Hz 40 Hz – 300 kHz

[4]

3 Hz – 5 Hz 5 Hz – 10 Hz

[4]

10 Hz – 5 kHz

[7]

3 Hz – 5 Hz 5 Hz – 10 Hz 10 Hz – 5 kHz

[5]

1.00 + 0.03

0.35 + 0.03

0.04 + 0.03

0.10 + 0.05

0.55 + 0.08

4.00 + 0.50

1.00 + 0.05

0.35 + 0.05

0.04 + 0.05

0.10 + 0.10

0.55 + 0.20

4.00 + 1.25

0.10

0.05

0.03

0.006

1.00 + 0.04

0.30 + 0.04

0.10 + 0.04

1.00 + 0.5

0.30 + 0.5

0.10 + 0.5

1.00 + 0.04

0.35 + 0.04

0.05 + 0.04

0.11 + 0.05

0.60 + 0.08

4.00 + 0.50

1.00 + 0.08

0.35 + 0.08

0.05 + 0.08

0.11 + 0.12

0.60 + 0.20

4.00 + 1.25

0.10

0.05

0.03

0.01

1.00 + 0.04

0.30 + 0.04

0.10 + 0.04

1.00 + 0.5

0.30 + 0.5

0.10 + 0.5

1.00 + 0.04

0.35 + 0.04

0.06 + 0.04

0.12 + 0.05

0.60 + 0.08

4.00 + 0.50

1.00 + 0.08

0.35 + 0.08

0.06 + 0.08

0.12 + 0.12

0.60 + 0.20

4.00 + 1.25

0.10

0.05

0.03

0.01

1.00 + 0.04

0.30 + 0.04

0.10 + 0.04

1.00 + 0.5

0.30 + 0.5

0.10 + 0.5

0.100 + 0.004

0.035 + 0.004

0.005 + 0.004

0.011 + 0.005

0.060 + 0.008

0.20 + 0.02

0.100 + 0.008

0.035 + 0.008

0.005 + 0.008

0.011 + 0.012

0.060 + 0.020

0.20 + 0.05

0.100 + 0.006

0.035 + 0.006

0.015 + 0.006

0.100 + 0.06

0.035 + 0.06

0.015 + 0.06

Additional Low Frequency Error for ACV, ACI (% of reading) Additional Error for Frequency, Period (% of reading)

Frequency

10 Hz - 20 Hz 20 Hz - 40 Hz 40 Hz - 100 Hz 100 Hz - 200 Hz 200 Hz - 1 kHz > 1 kHz

AC Filter

Slow

0 0 0 0 0 0

AC Filter

Medium

0.74

0.22

0.06

0.01

AC Filter

Fast

— —

0.73

0.22 0 0

0.18

0

Frequency

3 Hz - 5 Hz 5 Hz - 10 Hz 10 Hz - 40 Hz 40 Hz - 100 Hz 100 Hz - 300 Hz 300 Hz - 1 kHz > 1 kHz

6

1

⁄

2

Digits

0 0 0 0 0 0 0

1

5

⁄

Digits

2

0.12

0.17

0.2

0.06

0.03

0.01 0

1

4

⁄

Digits

2

0.12

0.17

0.2

0.21

0.07

0.02

0.005

0.001

[1] Specifications are for 1 hour warm up and 6 [2] Relative to calibration standards

1

⁄

digits, Slow ac filter

2

[3] 20% over range on all ranges except 300 Vac and 1 Aac ranges [4] For sinewave input > 5% of range. For inputs from 1% to 5% of range and < 50 kHz, add 0.1% of range additional error. [5] Typically 30% of reading error at 1 MHz, limited to 1x10

8

V Hz [6] Input > 100 mV. For 10 mV inputs, multiply % of reading error x 10. [7] Specified only for inputs > 10 mA

18

Chapter 1 Specifications

AC Measurement and Operating Characteristics

1

AC Measurement Characteristics

True RMS AC Voltage

Measurement Method:

AC-coupled True RMS – measures the ac component of input with up

[1]

to 300 Vdc of bias on any range Crest Factor : Additional Crest Factor Errors (non-sinewave):

Maximum 5:1 at Full Scale

[2]

Crest Factor 1-2: 0.05% of reading

Crest Factor 2-3: 0.15% of reading

Crest Factor 3-4: 0.30% of reading

Crest Factor 4-5: 0.40% of reading AC Filter Bandwidth: Slow Medium Fast Input Impedance: Input Protection:

3 Hz – 300 kHz

20 Hz – 300 kHz

200 Hz – 300 kHz

1 M

Ω ± 2%, in parallel with 150 pF

300 Vrms on all ranges

Frequency and Period

Measurement Method: Voltage Rang es: Gate Time: Measurement Timeout:

True RMS AC Current

Measurement Method:

Reciprocal c ount i ng tec hni qu e

Same as AC Voltage function

1s, 100 ms, or 10 ms

Selectable 3 Hz, 20 Hz, 20 0 Hz LF li mit

Direct coupled to the fuse and

shunt. AC-coupled True RMS

measurement (measures the

ac component only)

5

Shunt Resistance: Input Protection:

Measurement Noi se Rejection

Ω for 10 mA; 0.1Ω for 100 mA, 1A

1.5A 250 V fuse on 34901A module

[3]

AC CMRR: 70 dB

Measurement Considerations (Frequency and Period)

All frequency counters are susceptible to error when measuring low-voltage, low-frequency signals. Shielding inputs from external noise pickup is critical for minimizing measurement errors.

AC Operating Characteristics

Function

ACV, ACI:

1

6

Single Channel Measurement Rates Function

ACV:

Frequency, Period:

[5]

Digits

1

6

⁄

2

1

6

⁄

2

1

6

⁄

2

1

6

⁄

2

⁄

2üxç31ç33 Çä 32é

Resolution

1

6

⁄

Slow (3 Hz)

2

1

6

⁄

Medium (20 Hz)

2

1

⁄

Fast (200 Hz)

6

2

1

6

⁄

2üxç31ç33 Çä 32é

1

6

⁄

Digits (1s gate)

2

1

⁄

Digits (1s gate)

6

2

1

5

⁄

Digits (100 ms)

2

1

5

⁄

Digits (100 ms)

2

1

4

⁄

Digits (10 ms)

2

1

4

⁄

Digits (10 ms)

2

[4]

Readings/s

7 sec/reading

1

[6]

8

10

[7]

100

[8]

[7]

AC Filter

Slow (3 Hz) Medium (20 Hz) Fast (200 Hz) Fast (200 Hz) Fast (200 Hz)

Readings/s

0.14 1 8

100

0.77 1

2.5 9

3.2

70

[1] 300 Vrms isolation voltage (ch-ch, ch-earth) [2] For frequencies below 100 Hz, slow AC filter specified for sinewave input only [3] For 1 k

Ω unbalance in LO lead

[4] Maximum reading rates for 0.01% of ac step additional error. Additional settling delay required when input dc level varies.

1

[5] 6

⁄

digits=22 bits, 5

2

[6] For external trigger or remote operation using default

1

⁄

digits=18 bits, 4

2

1

⁄

digits=15 bits

2

settling delay (Delay Auto) [7] Maximum limit with default settling delays defeated [8] For fixed function and range, readings to memory, scaling and alarms turned off

19

Chapter 1 Specifications

Measurement Rates and System Characteristics

Single Channel Meas ure me nt Rate s

Function

DCV, 2-Wire Ohms:

Thermocouple:

RTD, Thermistor:

ACV:

Frequency, Period:

System Speeds

INTO Memory

Single Channel DCV 34902A Scanning DCV 34907A Scanning Digital Input 34902A Scanning DCV, scaling and 1 alarm fail 34907A Scanning Totalize 34902A Scanning T emperature 34902A Scanning ACV 34902A Scanning DCV/Ohms, alternate channels 34901A/34908A Scanning DCV

Resolution

1

⁄

(10 PLC)

6

2

1

5

⁄

(1 PLC)

2

1

4

⁄

(0.02 PLC)

2

0.1

°C (1 PLC)

(0.02 PLC)

0.01

°C (10 PLC)

0.1

°C (1 PLC)

°C (0.02 PLC)

1

⁄

Slow (3 Hz)

6

2

1

⁄

Medium (20 Hz)

6

2

1

⁄

Fast (200 Hz)

6

2

[3]

1

6

⁄

2

1

⁄

Digits (1s gate)

6

2

1

5

⁄

Digits (100 ms)

2

1

4

⁄

Digits (10 ms)

2

[4]

[3]

[1] [2]

Readings/s

6 (5) 53 (47) 490

49 (47) 280

6 (5) 47 (47) 280

0.14 1 8 100

1 9 70

Ch/s

490 250 250 220 170 160 100

90 60

INTO and OUT of Memory to GPIB or RS-232 (INIT, FETCh)

34902A Scanning DCV 34902A Scanning DCV with Time stamp

OUT of Memory to GPIB

[5]

Readings Readings with Time stamp Readings with all Format Options ON

180 150

800 450 310

OUT of Memory to RS-232

Readings Readings with Time stamp Readings with all Format Options ON

600 320 230

DIRECT to GPIB or RS-232

Single Channel DCV 34902A Scanning DCV Single Channel MEAS DCV 10 or MEAS DCV 1 Single Channel MEAS DCV or MEAS OHMS

440 200

25 12

System Characteristics

Scan Triggering

Scan Count: Scan Interval: Channel Delay: External Trig Delay: External Trig Jitter:

Alarms

Alarm Outputs: Latency:

Memory

Readings: Time Stamp Resolution: Relative Absolute States: Alarm Queue:

General Specifications

Power Supply: Power Line Frequency: Power Consumption: Operating Environment:

Storage Environment: Weight (Mainframe): Safety: RFI and ESD: Warranty:

[1] Reading speeds for 60 Hz and (5 0 Hz) operation; autozero OFF [2] For fixed function and range, readings to memory, scaling and alarms off, autozero OFF [3] Maximum limit with default settling delays defeated [4] Speeds are for 4 Using 115 kbaud RS-232 setting. [5] Assumes relative time format (time since start of scan) [6] Storage at temperatures above 40

This ISM device complies with Cana dian ICES-001. Cet appareil ISM est conforme à la norme NMB-001

du Canada.

N10149

1 to 50,000 or continuous 0 to 99 hours; 1 ms step size 0 to 60 seconds/channel; 1 ms step size < 300

µs; With Monitor On, < 200 ms

< 2 ms

4 TTL compatible. Select able TTL l ogic HI or LO on Fail 5 ms (typical)

Battery Backed, 4 year typical life 50,000 readings

1 ms 1 s 5 instrument states Up to 20 events

100 V / 120 V / 220 V / 240 V 45 Hz to 66 Hz automatically sensed (12 W) 25 VA peak Full accuracy for 0 Full accuracy to 80% R.H. at 40

°C to 70 °C

-40

°C to 55 °C

[6]

Net: 3.6 kg (8.0 lbs) Conforms to CSA, UL-1244, IEC 1010 Cat I CISPR 11, IEC 801/2/3/4 3 years

1

⁄

digits, delay 0, display off, autozero off.

2

°C will decrease battery life

[6]

±10%

°C

20

Chapter 1 Specifications

Module Specifications

34901A, 34902A, 34908A, 34903A, 34904A

General 34901A

Number of Channels 20+2 16 40 20 4x8

2/4 wire 2/4 wire 1 wire SPDT 2 wire Connects to Internal DMM Yes Yes Yes No No Scanning Speed Open/Close Speed 120/s 120/s 70/s 120/s 120/s

Maximum Input

Voltage (dc, ac rms) 300 V 300 V 300 V 300 V 300 V Current (dc, ac rms ) 1 A 50 mA 1 A 1 A 1 A Power (W, VA) 50 W 2 W 50 W 50 W 50 W Isolation (ch-ch, ch-earth) dc, ac rms 300 V 300 V 300 V 300 V 300 V

DC Characteristi cs

Offset Voltage Initial Closed Channel R Isolation (ch-ch, ch-earth) > 10 GΩ > 10 GΩ > 10 GΩ > 10 GΩ > 10 GΩ

AC Characteristi cs

Bandwidth 10 MHz 10 MHz 10 MHz 10 MHz 10 MHz Ch-Ch Cross Talk (dB) Capacitance HI to LO < 50 pF < 50 pF < 50 pF < 10 pF < 50 pF Capacitance LO to Earth < 80 pF < 80 pF < 80 pF < 80 pF < 80 pF Volt-Hertz Limit

Other

T/C Cold Junction Accuracy Switch Life No Load (typical) 100M 100M 100M 100M 100M Switch Life Rated Load (typical) Temperature Operating All Modules – 0 Temperature Storage All Modules – -20 Humidity (non-condensing) All Modules – 40

[1]

[2]

[3]

10 MHz -45 -45 -18

60 ch/s 250 ch/s 60 ch/s

< 3 µV< 6 µV< 3 µV< 3 µV< 3 µV

< 1Ω < 1Ω < 1Ω < 0.2Ω < 1Ω

10

[2] [5]

(typical) 0.8 °C0.8 °C0.8 °C

[6]

100k 100k 100k 100k 100k

Multiplexer Actuator Matrix

34902A 34908A 34903A 34904A

[4]

8

108 108 108 108

[7]

°C to 55 °C

°C to 70 °C

°C / 80% R.H.

-45 -33

1

⁄

[1] Speeds are for 4 [2] Errors included in the DMM measurement accuracy specifications [3] 50

Ω source, 50Ω load

digits, delay 0, display off, autozero off. Using 115 kbaud RS-232 setting.

2

[4] Isolation within channel 1 to 20 or 21 to 40 banks is -40 dB [5] Thermocouple specifications not guaranteed when 34907A module is present [6] Applies to resistive loads only [7] Thermocouple measurements not recommended with 34908A module due to common LO configuration.

21

Chapter 1 Specifications

Module Specifications

34905A, 34906A

RF Multiplexer

General 34905A 34906A

Number of Channels Dual 1x4

Open/Close Speed 60/s

Maximum Input

Voltage (dc, ac rms) 42 V Current (dc, ac rms) 0.7 A Power (W, VA) 20 W

DC Characteristi cs

Offset Voltage Initial Closed Channel R Isolation (ch-ch, ch-earth) > 1 GΩ

Other

Switch Life No Load (typical) 5M Switch Life Rated Load (ty pical) Temperature Operating 0 Temperature Storage -20 Humidity (non-condensing) 40

[1]

50

[2]

Dual 1x4

Ω

< 6 µV

< 0.5Ω

100k

°C to 55 °C

°C to 70 °C

°C / 80% R.H.

75

Ω

The ac performance graphs are shown on the following page.

AC Characteristics 34905A 34906A

Bandwidth Insertion Loss (dB) 10 MHz -0.1 -0.1 100 MHz -0.4 -0.4 500 MHz -0.6 -0.5 1 GHz -1.0 -1.0

1.5 GHz -1.2 -1.5 2 GHz -3.0 -2.0 SWR 10 MHz 1.02 1.02 100 MHz 1.05 1.05 500 MHz 1.20 1.25 1 GHz 1.20 1.40

1.5 GHz 1.30 1.40 2 GHz 1.40 2.00 Ch-Ch Cross T a lk (dB) 100 MHz -85 -75 500 MHz -65 -65 1 GHz -55 -50

1.5 GHz -45 -40 2 GHz -35 -35 Risetime < 300 ps Signal Delay < 3 ns Capacitance HI to LO < 20 pF Volt-Hertz Limit 10

[3]

2 GHz 2 GHz

[4]

10 MHz -100 -85

10

[1] Errors included in DMM meas ur ement a ccur acy sp eci f ica tio ns [2] Applies to resistive loads only [3] Bandwidth direct to module SMB connectors [4] 50

Ω source, 50Ω load

22

Chapter 1 Specifications

Typical AC Performance Graphs

Typical AC Performanc e Gr aphs

34905A, 34906A

1

Insertion Loss (50Ω)

VSWR (50Ω)

Direct to Module Using provided adapter cables

Insertion Loss (75Ω)

VSWR (75Ω)

Crosstalk (50Ω)

Crosstalk (75Ω)

23

Chapter 1 Specifications

Module Specifications

34907A

Digital Input / Output

Port 1, 2:

in(L):

V V

in(H):

V

out(L): out(H):

V

in(H) Max:

V Alarming: Speed Latency Read/Write Speed:

Totalize Input

Maximum Count: Totalize Input:

Signal Level: Threshold:

Gate Input: Count Reset: Read Speed:

8 Bit, input or output, non-isolated < 0.8V (TTL) > 2.0V (TTL) < 0.8V @ Iout = - 400 mA > 2.4V @ Iout = 1 mA < 42V with extern al open dr ai n p ul l- up Maskable pat ter n ma tc h or st at e ch an ge 4 ms (max) alarm sampling 5 ms (typical) to 34970A alarm output 95/s

26

2

- 1 (67,108,863) 100 kHz (max), rising or falling edge, programmable 1 Vp-p (min) 42 Vpk (max) 0V or TTL, jumper selectable TTL-Hi, TTL-Lo, or none Manual or Read+Reset 85/s

Software Specifications

BenchLink Data Logge r

System Requirements

PC Hardware: Operating System:

Computer Interfaces

GPIB:

LAN-to-GPIB: RS-232 (Serial Port):

Performance

Scan and Save to Disk:

[1] Software provided on CD-ROM; includes utility to create floppy disks for installation [2] Interface and dr ive rs mus t be pu rch ase d a nd in st al le d se pa rat el y [3] 90 MHz Pentium

[3]

®

, 20 MB RAM

(not included with Option 001)

[1]

486, 66 MHz, 16 MB RAM, 12 MB disk space Windows Windows NT

[2]

Agilent 82335B, 82340A/B/C, 82341A/B/C/D National Inst r ument s A T-G PIB / TNT, PCI-GPIB Agilent E581 0A (Windows 98/Me/ NT/2000/XP Professional) PC COM 1 to 4

100 ch/s, 2 strip charts displayed

®

3.1, Windows 95,

®

4.0

Analog Voltage (DAC) Output

DAC 1, 2: Resolution: I

out:

Settling Time: Accuracy: 1 year Temp Coefficient:

[1] Limited to 40 mA total for all three slots (six DAC channels)

±5 °C

±12V, non-isolated (earth referenced)

1 mV 10 mA max 1 ms to 0.01% of output

±(% of output + mV)

0.25% + 20 mV

±(0.015% + 1 mV) / °C

[1]

24

Chapter 1 Specifications

Product and Module Dimensions

103.6 mm

1

254.4 mm

TOP

374.0 mm

88.5 mm

348.3 mm212.6 mm

Module

315.6

91.9

All dimensio ns are shown

in millimeters .

25

Chapter 1 Specifications

To Calculate Total Measurement Error

Each specification includes correction factors which account for errors present due to operational limitations of the internal explains these errors and shows how to apply them t o your measurements. Refer to “Interpreting Internal DMM Specifications,” starting on page 28, to get a better understanding of the terminology used and to help you interpret the internal

DMM’s specifications.

DMM. This section

The internal

DMM’s accuracy specifications are expressed in the form:

(% of reading + % of range). In addition to the reading error and range error, you may need to add additional errors for certain operating conditions. Check the li st below to mak e sure you inc lude all mea surement errors for a given function. Also, make sure you apply the conditions as described in the footnotes on the specification pages.

• If you are operating the internal DMM outside the 23 °C ± 5 °C

temperature range specified, apply an additional temperature coefficient error.

• For dc voltage, dc current, and resistance measurements, you may

need to apply an additional reading speed error.

• For ac voltage and ac current measurements, you may need to apply

an additional low frequency error or crest factor error.

Understanding the “ % of reading ” Error The reading error compensates for inaccur acies that result from the function and range you select, as well as the input signal level. The reading error varies according to the input level on the selected range. This error is expressed in percent of reading. The following table shows the reading error applied to the internal

Range Input Level

DMM’s 24-hour dc voltage specification.

Reading Error (% of reading)

Reading

Error Voltage

26

10 Vdc 10 Vdc 10 Vdc

10 Vdc

1 Vdc

0.1 Vdc

0.0015

≤ 150 µV

≤ 15 µV ≤ 1.5 µV

Chapter 1 Specifications

To Calculate Total Measurement Error

Understanding the “ % of range ” Error The range error compensates for inaccuracies that result from the function and range you select. The range error contributes a constant error, expressed as a percent of range, independent of the input signal level. The following table shows the range error applied to the

DMM’s 24-hour dc voltage specification.

1

Range Input Level

10 Vdc 10 Vdc 10 Vdc

10 Vdc

1 Vdc

0.1 Vdc

Range Error (% of range)

0.0004

Range

Error Voltage

≤ 40 µV ≤ 40 µV ≤ 40 µV

Total Measurement Error To compute the total measurement error, add the reading error and range error. You can then convert the total measurement error to a “percent of input” error or a “ppm (part-permillion) of input” error as shown below.

% of input error =

ppm of input error =

Example: Computing Total Measurement Error

Total Measurement Error

Input Signal Level

Total Measurement Error

Input Signal Level

× 100

× 1,000,000

Assume that a 5 Vdc signal is input to the DMM on the 10 Vdc range. Compute the total measurement error using the 90-day accuracy specification of

±(0.0020% of reading + 0.0005% of range).

Reading Error = 0.0020% x 5 Vdc = 100 Range Error = 0.0005% x 10 Vdc = 50 Total Error = 100

µV + 50 µV= ± 150 µV

=

± 0.0030% of 5 Vdc

=

± 30 ppm of 5 Vdc

µV

27

Chapter 1 Specifications

Interpreting Internal DMM Specifications

This section is provided to give you a better understanding of the terminology used and will help you interpret the internal specifications.

Number of Digits and Overrange

The “number of digits” specification is the most fundamental, and sometimes, the most confusing characteristic of a multimeter. The number of digits is equal to the maximum number of “9’s” the multimeter can measure or display. This indicates the number of full digits. Most multimeters have the ability to overrange and add a partial or “

1

⁄

” digit.

2

DMM’s

For example, the internal range. This represents six full digits of resolution. The internal

DMM can measure 9.99999 Vdc on the 10 V

DMM

can also overrange on the 10 V range and measure up to a maximum of

12.00000 Vdc. This corresponds to a 6

1

⁄

-digit measurement with 20%

2

overrange capability.

Sensitivity

Sensitivity is the minimum level that the multimeter can detect for a given measurement. Sensitivity defines the ability of the multimeter to respond to small changes in the input level. For example, suppose you are monitoring a 1 mVdc signal and you want to adjust the level to within measurement would require a multimeter with a sensitivity of at least 1 range. You could also use a 4

For ac voltage and ac current measurements, note that the smallest value that can be measured is different from the sensitivity. For the internal the selected range. For example, the internal to 1 mV on the 100 mV range.

±1 µV. To be able to respond to an adjustment this small, this

µV. You could use a 6

DMM, these functions are specified to measure down to 1% of

1

⁄

-digit multimeter if it has a 1 Vdc or smaller

2

1

⁄

-digit multimeter with a 10 mVdc range.

2

DMM can measure down

28