Agilent Technologies 34970A User Manual

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User’s Guide

Publication Number 34970-90003 (order as 34970-90101 manual set) Edition 3, March 2003

see the pages following the Index.

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

Flexible Data Acquisition / Switching Features

• 6

⁄

-digit multimeter accuracy, stability, and noise rejection

• 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) compatibilit y

Agilent 34970A Data Acquisition / S witch Unit

The Front Panel at a Glance

Denotes a menu key. See the next page for details on menu operation.

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 Control 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

The Front-Panel Menus at a Glance

Several of the front-panel keys guide you through menus to configu re 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 automaticall y 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.

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 turn off. 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 errors. Instrument is configured for an external scan interval. Scan Once mode is enabled. Press to initiate 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 annun ciators, hold down the key as you turn on the instrument.

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 pages 83 and 128)

3 RS-232 Interface Connector

Use the Menu to:

• Select the GP-IB or RS-232 interface (see chapter 2).

• Set the GP-IB address (see chapter 2).

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

4 Power-Line Fuse-Holder Assembly 5 Power-Line Voltage Setting 6 Chassis Ground Screw 7 GP-IB (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.

BenchLink Data Logger Software at a Glance

Agilent BenchLink Data Logger is a Windows-based application designed to make it easy to use the 34970A with your and analyzing measurements. Use the software to set up your test, acquire and archive measurement data, and perform real-time display and analysis of your incoming measurements.

BenchLink Data Logger’s key functions include the following:

• Configure measurements on the spreadsheet-like Scan Setup page.

• Display measurements graphically using the real-time Data Grid,

Strip Chart, Readout, Bar Meter, XY Plot, and Histogram wind ows.

• Add or configure graphics at any time.

• Use graphical controls to set output voltages, close channels, output

digital values, or view alarms.

• Copy measurement data and graphics to a file or to the Clipboard for

use in other applications.

• Add textual annotation and explanations to measurement results and

test reports.

• Track readings on a single channel through the Monitor toolbar.

• Enter information into the Event Log automatically or manually

while acquiring measurement data or during post-scan analysis.

• Print scan setups, event logs, and graphics.

• Communicate with the instrument using GPIB, RS-232, modem,

or LAN (using a LAN-to-GPIB gateway).

PC for gathering

To install the software, refer to “Installing BenchLink Data Logger Software” on page 18.

To learn more about the software and its capabilities, refer to the On-Line Help System for BenchL ink Data Logger.

The Plug-In Modules at a Glance

For complete s pecifications on each plug-in module, refer to the module sections in chapter 9.

34901A 20-Channel Armature Mu ltip le xer

• 20 channels of 300 V switching

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

• Built-in thermocouple reference junction

• Switching speed of up to 60 channels per second

• Connects to the internal multimeter

• For detailed information and a module diagram, see page 164.

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 Mult iple xer

• 16 channels of 300 V switching

• Built-in thermocouple reference junction

• Switching speed of up to 250 channels per second

• Connects to the internal multimeter

• For detailed information and a module diagram, see page 166.

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 ca n cl ose mu lt ipl e c ha nn els on t h is modul e only if you have not configured any channels to be part of the scan list. Otherwi se, all channels on the module are break-before-make.

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

• 300 V, 1 A actuation and switching

• SPDT (Form C) latching relays

• Breadboard area for custom circuits

• For detailed information and a module diagram, see page 168.

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 Matri x S witch

• 32 two-wire crosspoints

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

• 300 V, 1 A switching

• For detailed information and a module diagram, see page 170.

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

• For detailed information and a module diagram, see page 172.

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

34907A Multifunction Module

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

• 100 kHz Totalize input with 1 Vpp sensitivity

• Two ±12 V Calibrated Analog Outputs

• For detailed information and module block diagrams, see page 174.

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- End ed Mu ltip le xer

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

• Built-in thermocouple reference junction

• Switching speed of up to 60 channels per second

• Connects to the internal multimeter

• For detailed information and a module diagram, see page 176.

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

In This Book

Quick Start Chapter 1 helps you get familiar with a few of the instrument’s front-panel features. This chapter also shows how to install the BenchLink Data Logger software.

Front-Panel Overview Chapter 2 introduces you to the front-panel menus and describes some of the instrument’s menu features.

System Overview Chapter 3 gives an overview of a data acquisition system and describes how parts of a sy stem work together.

Features and Functions Chapter 4 gives a detailed description of the instrument’s capabilities and operation. You will find this chapter useful whether you are operating the instrument from the front panel or over the remote interface.

Remote Interface Reference Chapter 5 contains reference information to help you program the instrument over the remote interface using the

Error Messages Chapter 6 lists the error messages that may appear as you are working with the instrument. Each listing contains enough information to help you diagnose and solve the problem.

SCPI language.

Application Programs Chapter 7 contains several remote interface program examples to help you develop programs for your application.

Tutorial Chapter 8 discusses measurement considerations and techniques to help you obtain the best accuracies and reduce sources of measurement noise.

Specifications Chapter 9 lists the technical specifications for the mainframe and plug-in modules.

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 year s of original purchase, Agile nt will either repair or replac e it free of charge. C all 1-877-447-7278 and ask for “Express Exchange” or contact your local Agilent office.

Contents

Chapter 1 Quick Start

To Prepare the Instrument for Use 17 Installing BenchLink Data Logger Software 18 To Connect Wiring to a Module 20 To Set the Time and Date 22 To Configure a Channel for Scanning 23 To Copy a Channel Configuration 25 To Close a Channel 26 If the Instrument Does Not Turn On 27 To Adjust the Carrying Handle 29 To Rack Mount the Instrument 30

Chapter 2 Front-Panel Overview

Front-Pa nel Menu Reference 35 To Monitor a Single Ch an ne l 37 To Set a Scan Interval 38 To Apply Mx+B Scaling to Measurements 39 To Configure Alarm Limits 40 To Read a Digital Input Port 42 To Write to a Digital Output Port 43 To Read the Totalizer Count 44 To Output a DC Voltage 45 To Configure the Remote Interface 46 To Store the Instr u me nt S tat e 48

Chapter 3 System Overv iew

Data Acquisition System Overview 50 Signal Routing and Switching 57 Measurement Input 60 Control Output 67

Contents

Chapter 4 Features and Functions

SCPI Language Conventions 73 Scanning 74 Single-Channel Monit oring 93 Scanning With Extern al Ins tr um ent s 95 General Measurement Configuration 98 Temperature Measurement Configuration 106 Voltage Measurement Configuration 113 Resistance Meas ure me nt Con f iguration 115 Current Measurement Configuration 116 Frequency Measure ment Configuration 118 Mx+B Scaling 119 Alarm Limits 122 Digital Input Operations 133 Totalizer Operations 135 Digital Output Operations 138 DAC Output Operations 139 System-Related Operations 140 Remote Interface Configuration 150 Calibration Overview 155 Factory Reset State 160 Instrument Pr es et S tat e 161 Multiplexer Module Default Settings 162 Module Overvi ew 163 34901A 20-Channe l Mu lti p le xer 164 34902A 16-Channe l Mu lti p le xer 166 34903A 20-Channe l Ac tuator 168 34904A 4x8 Matrix Sw it ch 170 34905A/6A Dual 4-Channel RF Multiplexers 172 34907A Multifunction Module 174 34908A 40-Channel Sin g le -Ende d Mul t ipl exe r 176

Contents

Chapter 5 Remote Interface Reference

SCPI Command Summary 181 Simplified Programming Overview 201 The MEASure? and CONFigure Commands 207 Setting the Function, Range, and Resolution 214 Temperature Configuration Commands 219 Voltage Configuration Commands 223 Resistance Configuration Commands 224 Current Configuration Commands 224 Frequency Configuration Commands 225 Scanning Over v i ew 226 Single-Channel Monitori ng Overview 237 Scanning With an Externa l In str u me nt 239 Mx+B Scaling Overview 244 Alarm System O v er v i ew 247 Digital Input Commands 255 Totalizer Commands 256 Digital Output Commands 258 DAC Output Commands 2 58 Switch Control Commands 259 State Storage Commands 261 System-Related Commands 264 Interface Configuration Commands 269 RS-232 Interface Configuration 270 Modem Communications 274 The SCPI Status System 275 Status System Comma nds 286 Calibration Commands 292 Service-Related Commands 294 An Introduction to the SCPI Language 296 Using Device Clear 302

Contents

Chapter 6 Error Messages

Execution Errors 305 Instrument Errors 309 Self-Test Errors 314 Calibration Errors 315 Plug-In Module Errors 317

Contents

Chapter 7 A ppl ic ation Programs

Example Programs for Excel 7.0 321 Example Programs for C and C++ 328

Chapter 8 Tuto rial

System Cabling and Connections 335 Measurement Fundamentals 343 Low-Level Signal Multiplexing 378 Actuators and G en er a l-P u r p os e S w it ching 384 Matrix Switch ing 388 RF Signal Multiplexing 390 Multifunction Mo d ul e 392 Relay Life and Preventative Maintenance 399

Chapter 9 Specifi cations

DC, Resistance, and Temperature Accuracy Specifications 404 DC Measurement and Operating Charact eristics 405 AC Accuracy Specifications 406 AC Measurement and Operating Cha racteristics 407 Measurement Rate s an d Sys t em Char a c ter i sti c s 408 Module Specifications 409 BenchLink Data Logger Software Specifications 412 Product and Module Dimensions 413 To Calculate Total Measurement Error 414 Interpreting Internal DMM Specifications 416 Configuring for Highest Accuracy Measurements 419

Index

Quick Start

One of the first things you will want to do with your instrument is to become acquainted with the front panel. We have written the exercises in this chapter to prepare the instrument for use and help you get familiar with some of its front-panel operations.

The front panel has several groups of keys to select various functions and operations. A few keys have a shifted function printed in blue below

the key. To perform a shifted function, press (the will turn on). Then, press the key that has the desired label below it.

For example, to select the Utility Menu, press .

SHIFT annunciator

If you accidentally press , just press it again to turn off the annunciator.

This chapter is divided into the following sections:

• To Prepare the Instrume nt for Use, on page 17

• Installing BenchLink Data Logger Software, on page 18

• To Connect Wiring to a Module, on page 20

• To Set the Time and Date, on page 22

• To Configure a Channel for Scanning, on page 23

• To Copy a Channel Configuration, on page 25

• To Close a Ch annel, on page 26

• If the Instrument Does Not Turn On, on page 27

• To Adjust the Carrying Handle, on page 29

• To Rack Mount the Instrument, on page 30

SHIFT

Chapter 1 Quick Start

To Prepare the Instrument for Use

1 Check the list of supplied items.

Verify that you have received the following items with your instrument. If anything is missing, contact your nearest Agilent Technologies Sales Office.

One power cord. This User’s Guide. One Service Guide. One Quick Reference Guide. Certificate of Calibration (if you ordered the internal DMM). Quick Start Package (if you ordered the internal DMM):

• One RS-232 cable.

• BenchLink Data Logger Software CD-ROM.

To install the software, see page 18.

• One J-type thermocouple and a flatblade screwdriver.

Any plug-in modules that you ordered are delivered in a separate shipping container.

On/Standby Switch

WARNING

Note that this switch

Standby only.

is To disconnect t he mains from the instrumen t, remove the power cord.

2 Connect the power cord and turn on the instrument.

The front-panel display will light up briefly while the instrument performs its power-on self-test. The

GPIB address is also displayed.

The instrument initially powers up with all measurement channels turned off. To review the power-on display with all annunciators

turned on, hold down as you turn on the instrument. If the

instrument does not turn on properly, see p age 27.

3Perform a complete self-test.

The complete self-test performs a more extensive set of tests than those performed at power-on. Hold down as you turn on the instrument

and hold down the ke y until you hear a long beep. The self-test will begin when you release the key following the beep.

If the self-test fails, see the 34970A Se rvice Guide for instructions on returning the instrument to Agilent for service.

Chapter 1 Quick Start

Installing BenchLink Data Logger Software

If you ordered the 34970A with the internal DMM, then the BenchLink Data Logger software is included. The software is shipped on one

CD-ROM, but includes a utility to build installation floppy disks.

To install the software on your of free disk space.

For system requirements and additional details on the features of the software, refer to the specifications in chapter 9.

Installation Procedure

PC, you will need a minimum of 12 MB

If you are running Windows 95 or Windows NT 4.0

1. Insert the CD-ROM into your drive.

2. Select the

3. Select the sheet. Click on

If you are running Windows

1. Insert the

2. Select

3. Type <drive>

CD-ROM drive. Click OK to continue and follow the on-screen

Settings | Control Panel from the Start menu. Double-click on

Add/Remove Programs icon.

Install/Uninstall tab on the Add/Remove Programs property

Install and follow the on-screen instructions.

3.1

CD-ROM into your drive.

File | Run from the Program Manager menu bar.

:\setup, where drive is the letter representing your

instructions.

Chapter 1 Quick Start

Installing BenchLink Data Logger Software

Creating Installation Floppy Disks

You have the option to create an installation on floppy disks from the

CD-ROM installation utility. This utility is provided so that you can

install BenchLink Data Logger on a computer that does not have a

CD-ROM drive.

Note: You will need a total of five (5) formatted floppy disks to create an installation.

1. Go to a computer that is equipped with a

2. Start the installation procedur e as described on the previous page.

3. Select procedures and follow the on-screen instructions.

Create disks... on the initial display of the installation

CD-ROM drive.

On-Line Help System

The software is shipped with an extensive on-line Help system to help you learn the features of the software as well as troubleshoot any problems that might arise as you are using t he software. As you are installing the software, you will notice that the on-line Help system is available in several languages.

Chapter 1 Quick Start

To Connect Wiring to a Module

1 Remove the module cover.

3 Route wiring through strain relief.

2 Connect wiring to the screw terminals.

20 AWG

Typical

6 mm

4 Replace the module cover.

Cable Tie Wrap

(optional)

5 Install the module into mainframe.

Channel Number:

Slot Channel

Wiring Hints...

• For detailed informat io n on eac h mo du le , refer to the section starting on page 16 3.

• To reduce wear on the internal DMM relays, wire like functions on adjacent chan ne ls .

• For information on grounding and shielding, see page 335.

• The diagrams on the next page show how to connect wiring to a mult ip le xe r mod ul e fo r each measurement function.

Chapter 1 Quick Start

To Connect Wiring to a Module

DC Voltage / AC Voltage / Frequency Thermocouple

Thermocouple Types: B, E, J, K, N, R, S, T

See page 351 for thermocouple color codes.

Ranges: 100, 1 k, 10 k, 100 k, 1 M, 10 M, 100 MΩ RTD Types: 0.00385, 0.00391 Thermistor Types: 2.2 k, 5 k, 10 k

DC Current / AC Current

Ranges: 100 mV, 1 V, 10 V, 100 V, 300 V

4-Wire Ohms / RTD 2-Wire Ohms / RTD / Thermistor

Channel n (source) is automatically paired with Channel n+10 (sense) on the 34901A or Channel n+8 (sense) on the 34902A.

Valid only on channels 21 and 22 on the 34901A.

Ranges: 10 mA, 100 mA, 1A

Ranges: 100, 1 k, 10 k, 100 k, 1 M, 10 M, 100 MΩ RTD Types: 0.00385, 0.00391

Chapter 1 Quick Start

To Set the Time and Date

All readings during a scan are automatically time stamped and stored in non-volatile memory. In addition, alarm data is time stamped and stored in a separate non-volatile memory queue.

Utility

1 Set the time of day.

Use and to select the field to modify and turn the knob to change the value. You can also edit the

AM/PM field.

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2 Set the date.

Use and to select the field to modify and turn the knob to change the value.

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Chapter 1 Quick Start

To Configure a Channel for Scanning

Any channel that can be “read” by the instrument can also be included in a scan. This includes readings on multiplexer channels, a read of a digital port, or a read of the count on a totalizer channel. Automated scanning is not allowed with the digital output, or voltage output (

1 Select the channel to be added to the sc an list.

Turn the knob until the desired channel is shown on the right side of front-panel display. The channel number is a three-digit number; the left-most digit represents the slot number (100, 200, or 300) and the two digits on the right indicate the channel number (102, 110, etc.).

Note: You can use and to skip to the beginning of the previous or next slot.

For this example, assume that you have the 34901A multiplexer installed in slot 100 and select channel 103.

RF multiplexer, matrix, actuator,

DAC) modules.

2 Select the measurement parameters for the selected channel.

Use the knob to scroll through the measurement choices on each level of the menu. When you press to make your selection, the menu

automatically guides you through all relevant choices to configure a measurement on the selected function. When you have finished configuring the parameters, you are automatically exited from the menu.

The current selection (or default) is displayed in full bright for easy identification. When you make a different selection, the new choice is shown in full bright and it becomes the default selection. The order of the choices always remains the same; however, you always enter the menu at the current (full bright) setting for each parameter.

Note: The menu will timeout after about 20 seconds of inactivity and any changes made previously will take effect.

For this example, con fi gur e ch a nne l 103 to mea sur e a J -type therm oc ouple with 0.1

°C of display resolution.

Chapter 1 Quick Start

To Configure a Channel for Scanning

Note: Press to sequentially step through the scan list and take a measurement on each channel (readings are not stored in memory). This is an easy way to verify your wiring connections before initiating the scan.

3 Run the scan and stor e the re ad ing s i n non- vo l at ile memo ry.

The instrument automatically scans the configured channels in consecutive order from slot 100 through slot 300 (the

SCAN annunciator

turns on). Channels that are not configured are skipped during the scan. In the default configuration, the instrument continuously scans the configured channels at a 10-second interval.

Press and hold to stop the scan.

4 View the data f rom t he scan.

All readings taken during a scan are automatically time stamped and stored in non-volatile memory. During the scan, the instrument calculates and stores the minimum, maximum, and average on all channels in the scan list. You can read the contents of memory at any time, even during a scan.

From the front panel, data is available for the last 100 readings on each channel readings taken during a scan (all of the data is available from the remote interface). From the View menu, select

READINGS and press

again. Then press and to choose the data you want to view

for the selected channel as shown in the table below.

and

Select Channel Last Reading on Channel

Time of Last Reading Minimum Reading on Channel Time of Minimum Reading Maximum Reading on Channel Time of Maximum Reading Average of Readings on Channel Second Most Recent Reading on Channel Third Most Recent Reading on Channel

99th Most Recent Reading on Channel

Chapter 1 Quick Start

To Copy a Channel Configuration

After configuring a channel to be included in the scan list, you can copy that same configuration to other channels in the instrument (including digital channels on the multifunction module). This feature makes it easy to configure several channels for the same measurement. When you copy the configuration from one channel to another, the following parameters are automatically copied to the new channel:

• Measurement configuration

• Mx+B scaling configuration

• Alarm configuration

• Advanced measurement configuration

1 Select the channel to copy the conf ig uratio n from.

Turn the knob until the desired channel is shown on the right side of front-panel display. For this example, let’s copy the configuration from channel 103.

2 Select the copy function.

Use the knob to scroll through the measurement choices until you see

COPY CONFIG. When you press to make your selection, the menu

automatically guides you to the next step.

3 Select the channel to copy the conf ig uratio n to.

Turn the knob until the desired channel is shown on the right side of front-panel display. For this example, let’s copy the configuration to channel 105.

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4 Copy the channel configuration to the selected cha nnel.

Note: To copy the same configuration to other channels, repeat this procedure.

Chapter 1 Quick Start

To Close a Channel

On the multiplexer and switch modules, you can close and open individual relays on the module. However, note that if you have already configured any multiplexer channels for scanning, you cannot independently close and open individual relays on that module.

1 Select the channel.

Turn the knob until the desired channel is shown on the right side of front-panel display. For this example, select channel 213.

2 Close the selected channel.

3 Open the selected channel.

Note: will sequentially open all channels on the module in the selected slot.

The table below shows the low-level control operations available for each of the plug-in modules.

Plug-In Module

34901A 20-Channel Mux 34902A 16-Channel Mux 34908A 40-Channel Single-Ended Mux 34903A 20-Channel Actuator 34904A 4x8 Matrix 34905A Dual 4-Channel RF Mux (50Ω) 34906A Dual 4-Channel RF Mux (75 34907A Multifun ction Module (DIO) 34907A Multifunction Module (Totalizer) 34907A Multifunction Module (DAC)

[1] Only one channel can be closed at a time on this module. [2] Only one channel in each bank can be closed at a time on this module.

Ω)

•••

[1]

[2] [2]

•••

••• •

••

•

•• •

••

•

Chapter 1 Quick Start

If the Instrument Does Not Turn On

Use the following steps to help solve problems you might encounter when turning on the instrument. If you need more help, refer to the 34970A Service Guide for instructions on returning the instrument to Agilent for service.

1 Verify that there is ac power to the instrument.

First, verify that the power cord is firmly plugged into the power receptacle on the rear panel of the instrument. You should also make sure that the power source you plugged the instrument into is energized. Then, verify that the instrument is turned on.

The On/Standby switch is located on the lower left side of the front panel.

2 Verify the powe r -li ne voltage setting.

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

Note: For 127 Vac operation, use the 120 Vac setting. For 230 Vac operation, use the 220 Vac setting.

See the next page if you need to change the line voltage setting.

3 Verify that the po wer-line fuse is good .

The instrument is shipped fr om the fact ory with a 50 0 mA fuse inst alled. This is the correct fuse for all line voltages.

See the next page if you need to replace the power-line fuse.

To replace the 500 mAT, 250 V fuse, order Agilent part number 2110-0458.

Chapter 1 Quick Start

If the Instrument Does Not Turn On

1 Remove the power cord. Remove the fuse-holder assembly from the rear panel.

3 Rotate the line-voltage selector until the

correct voltage appears in the window.

2 Remove the line-voltage selector from

the assembly.

Fuse: 500 mAT (for all line voltages) Agilent Part Number: 2110-0458

4 Replace the fuse-holder assembly in the rear panel.

100, 120 (127), 220 (230) or 240 Vac

Verify that the correct line voltage is selected and the power-line fuse is good.

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 Rack Mount the Instrument

You can mount the instrument 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 Agilent System II instrument of the same size can be rack-mounted beside the 34970A.

Note: Remove the carrying handle, and the front and rear rubber bumpers, before rack-mounting the instrument.

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

Front Rear (bottom view)

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

Chapter 1 Quick Start

To Rack Mount the Instrument

To rack mou n t a s in gl e in strument, o r de r a da p t er ki t 5063 -9 24 0.

To rack mount two instruments side-by-side, order lock-link kit 5061-9694 and flange kit 5063-9212. Be sure to use the support rails inside the rack cabinet.

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 Overview

This chapter introduces you to the front-panel keys and menu operation. 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 many front-panel operations. See chapter 4 “Features and Functions,” starting on page 71, for a complete discussion of the instrument’s capabilities and operation.

This chapter is divided into the following sections:

• Front-Panel Menu Reference, on page 35

• To Monitor a Single Channel, on page 37

• To Set a Scan Interval, on page 38

• To Apply Mx+B Scaling to Measurements, on page 39

• To Configure Alarm Limits, on page 40

• To Read a Digital Input Port, on page 42

• To Write to a Digital Output Port, on page 43

• To Read the Totalizer Count, on page 44

• To Output a DC Vo ltage, on page 45

• To Configure the Remote Interface, on page 46

• To Store the Instrument State, on page 48

Chapter 2 Front-Panel Overview

Front-Panel Menu Reference

This section gives an overview of the front-panel menus. The menus are designed to automatically guide you through all parameters required to configure a particular function or operation. The remainder of this chapter shows examples of using the front-panel menus.

Configure th e measurement parameters on th e displayed channel.

• Select measure me nt function (dc volts, oh ms , et c.) on the displayed channel.

• Select transducer type for temperature measurements.

• Select units (°C, °F, or K) for temperature measurements.

• Select measureme nt rang e or au to ran ge .

• Select measureme nt resolution.

• Copy and paste measurement confi gu r at io n to other channels.

Configure the scaling parameters for the displayed channel.

• Set the gain (“M”) and offset (“B”) value for the displayed channel.

• Make a null measurement and store i t as the offset value.

• Specify a custom la be l (RPM, PSI, etc.) for the disp la ye d ch an ne l.

Configure al arms on the displayed channel.

• Select one of fou r ala rms to report alarm condit io ns on th e displayed channe l.

• Configure a hi gh lim it , lo w lim it , or bo th for the displayed chan ne l.

• Configure a bit pa ttern which will gene rat e an ala rm (di gi t a l in pu t on ly ).

Configure the four Alarm Outp ut ha rdw a re li ne s.

• Clear the state of the four alarm outp ut lin es .

• Select the “Latch” or “Track” mode for the four alarm output lines.

• Select the slope (ris in g or fa ll ing edge) for the four alarm out pu t li ne s.

Configure the event or action that controls the scan interval.

• Select the scan int erv al mod e (in te rva l, manual, external, or al arm ).

• Select the scan cou nt.

Chapter 2 Front-Panel Overview

Front-Panel Menu Reference

Configure the advanced measurement features on displayed channel.

• Set the integration time for measurements on the displayed channel.

• Set the channel-to-channel del ay for scanning.

• Enable/disabl e th e th erm oc ou pl e ch ec k fe ature (T/C measurement s on ly ).

• Select the refere nce ju nc ti on source (T/C measureme nt s on ly ).

• Set the low frequency limit (ac measurements only).

• Enable/disable offset compensation (resistance measurements only).

• Select the binary or decimal mode for digital operations (digital input/output only).

• Configure the to ta lizer reset mode (total iz er on ly ).

• Select which edge is detected (rising or falling) for totalizer operations.

Configure system-related instrument parameters.

• Set the real-time system clock and calendar.

• Query the firmware revisions for the mainframe and installed modules.

• Select the inst rumen t ’ s pow er-o n co nf ig uration (last or factory reset).

• Enable/disable the internal DMM.

• Secure/unsecure the instrument for calibration.

View readings, alarms, and errors.

• View the last 100 sc anned readings from me mo ry (la st , min, max, and average ).

• View the first 20 alarms in the alar m queue (reading and time alarm occ urred).

• View up to 10 errors in the error queue.

• Read the number of cycles for the displayed relay (relay maintenance feature).

Store and recall in stru me nt sta tes.

• Store up to five inst rument states in non-volatile memory.

• Assign a name to ea ch storage location .

• Recall stored st ates, power-down sta te , fa ct ory rese t state, or preset sta te .

Configure the remote interface.

• Select the GPIB addre ss.

• Configure the RS -23 2 in te rfa ce (bau d rat e, pari ty , an d fl ow co ntrol).

Chapter 2 Front-Panel Overview

To Monitor a Single Channel

You can use the Monitor function to continuously take readings on a si ngle channel, even during a scan. This feature is useful for troubleshooting your system before a test or for watching an important signal.

1 Select the channel to be monitored.

Only one channel can be monitored at a time but you can change the channel being monitored at any time by turning the knob.

2 Enable monitoring on the selected cha nnel.

Any channel that can be “read” by the instrument can be monitored (the

MON annunciator turns on). This includes any combination of

temperature, voltage, resistance, current, frequency, or period measurements on multiplexer channels. You can also monitor a digital input port or the totalizer count on the multifunction module.

To disable monitoring, press again.

Chapter 2 Front-Panel Overview

To Set a Scan Interval

You can set the instrument’s internal timer to automatically scan at a specific interval (e.g., start a new scan sweep every 10 seconds) or when an external instrument to scan continuously or to stop after sweeping through the scan list a specified number of tim es.

1 Select the interv al s c an mo de .

For this example, select the Interval Scan mode which allows you to set the time from the start of one scan sweep to the start of the next scan sweep. Set the interval to any value between 0 and 99 hours.

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2 Select the scan count.

TTL trigger pulse is received. You can configure the

You can specify the number of times that the instrument will sweep through the scan list (the default is continuous). When the specified number of sweeps have occurred, the scan stops. Set the scan count to any number between 1 and 50,000 scans (or continuous).

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3 Run the scan and sto re t he r e ad ing s i n memo ry.

Chapter 2 Front-Panel Overview

To Apply Mx+B Scaling to Measurements

To Apply Mx+B S caling to Measu re ments

The scaling function allows you to apply a gain and offset to all readings on a specified multiplexer channel during a scan. In addition to setting the gain (“M”) and offset (“B”) values, you can also specify a custom measurement label for your scaled readings (

1 Configure the channel.

You must configure the channel (function, tra nsducer type, etc.) before applying any scaling values. If you change the measurement configuration, scaling is turned off on that channel and the gain and offset values are reset (M=1 and B=0).

2 Set the gain and of f s et va l ues .

The scaling values are stored in non-volatile memory for the specified channels. A Factory Reset turns off scaling and clears the scaling values on all channels. An Instrument Preset or Card Reset does not clear the scaling values and does not turn off scaling.

RPM, PSI, etc.).

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3 Select the custom label.

You can specify an optional three-character label for your scaled readings ( unit for the selected function (

RPM, PSI, etc.). The default label is the standard engineering

Set Gain

Set Offset

VDC, OHM, etc.).

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4 Run the scan and stor e the s c ale d re ad ing s i n memo ry.

Chapter 2 Front-Panel Overview

To Configure Alarm Limits

The instrument has four alarms which you can configure to alert you when a reading exceeds specified limits on a channel during a scan. You can assign a high limit, a low limit, or both to any configured channel in the scan list. You can assign multiple channels to any of the four available alarms (numbered 1 through 4).

1 Configure the channel.

You must configure the channel (function, tra nsducer type, etc.) before setting any alarm limits. If you change the measurement configuration, alarms are turned off and the limit values are cleared. If you plan to use Mx+B scaling on a channel which will also use alarms, be sure to configure the scaling values first.

2 Select which of the four al arms yo u want to use .

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3 Select the alarm mode on the selected channel.

You can configure the instrument to generate an alarm when a measurement exceeds the specified HI or LO limits (or both) on a measurement channel.

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Chapter 2 Front-Panel Overview

To Configure Alarm Limits

4 Set the limit value.

The alarm limit values are stored in non-volatile memory for the specified channels. The def ault val ues for the high an d low limi ts are “0”. The low limit must always be less than or equal to the high limit, even if you are using only one of the limits. A Factory Reset clears all alarm limits and turns off all alarms. An Instrument Preset or Card Reset does not clear the alarm limits and does not turn off alarms.

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5 Run the scan and sto re t he r e ad ing s i n memo ry.

If an alarm occurs on a channel as it is being scanned, then that channel’s alarm status is stored in reading memory as the readings are taken. Each time you start a new scan, the instrument clears all readings (including alarm data) stored in reading memory from the previous scan. As alarms are generated, they are also logged in an alarm queue, which is separate from reading memory. Up to 20 alarms can be logged in the alarm queue. Reading the alarm queue using the View menu clears the alarms in the queue.

Chapter 2 Front-Panel Overview

To Read a Digital Input Port

The multifunction module (34907A) has two non-isolated 8-bit input/output ports which you can use for reading digital patterns. You can read the live status of the bits on the port or you can configure a scan to include a digital read.

1 Select the Digital Input port.

Select the slot containing the multifunction module and continue turning the knob until

2 Read the specified port.

You can specify whether you want to use binary or decimal format. Once you have selected the number base, it is used for all input or output operations on the same port. To change the number base,

press the key and select

DIN is displayed (channel 01 or 02).

USE BINARY or USE DECIMAL.

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Bit 7 Bit 0

The bit pattern read from the port will be displayed until you press another key, turn the knob, or until the display times out.

Note: To add a digital input channel to a scan list, press and select the

DIO READ choice.

Binary Display Shown

Chapter 2 Front-Panel Overview

To Write to a Digital Output Port

The multifunction module (34907A) has two non-isolated 8-bit input/output ports which you can use for outputting digital patterns.

1 Select the Digital Output port.

Select the slot containing the multifunction module and continue turning the knob until

2 Enter the bit pattern editor.

DIN is displayed (channel 01 or 02).

Notice that the port is now converted to an output port (

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Bit 7 Bit 0

3 Edit the bit pattern.

Use the knob and or keys to edit the individual bit values. You can specify whether you want to use binary or decimal format. Once you have selected the number base, it is used for all input or output operations on the same port. To change the number base,

press the key and select

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4 Output the bit pattern to the specified port.

The specified bit pattern is latched on the specified port. To cancel an output operation in progress, wait for the display to time out.

Binary Display Shown

USE BINARY or USE DECIMAL.

Decimal Display Shown

DOUT).

Chapter 2 Front-Panel Overview

To Read the Totalizer Count

The multifunction module (34907A) has a 26-bit totalizer which can count pulses at a 100 kHz rate. You can manually read the totalizer count or you can configure a scan to read the count.

1 Select th e totalizer ch a n ne l .

Select the slot containing the multifunction module and continue turning the knob until

2 Configure the totalize mode.

The internal count starts as soon as you turn on the instrument. You can configure the totalizer to reset the count to “0” after being read or it can count continuously and be manually reset.

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TOTALIZE is displayed (channel 03).

3 Read the count.

The count is read once each time you press ; the count does not update automatically on the display. As configured in this example, the count is automatically reset to “0” each time you read it.

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The count will be displayed until you press another key, turn the knob, or until the display times out. To manually reset the totalizer count,

press .

Note: To add a totalizer channel to a scan list , press and select the

TOT READ choice.

Chapter 2 Front-Panel Overview

To Output a DC Volta ge

To Output a DC Voltage

The multifunction module (34907A) has two analog outputs capable of outputting calibrated voltages between

±12 volts.

1Select a

Select the slot containing the multifunction module and continue turning the knob until

2 Enter the output vo lta ge ed it or.

DAC Output channel.

DAC is displayed (channel 04 or 05).

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3 Set the desired output voltage.

Use the knob a nd or keys to edit the individual digits.

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4 Output the vol t ag e f r o m the se l ec t ed DAC.

The output voltage will be displayed until you press another key or turn the knob. To manually reset the output voltage to 0 volts, press .

Chapter 2 Front-Panel Overview

To Configure the Remote Interface

The instrument is shipped with both an GPIB (IEEE-488) interface and an The the factory.

GPIB Configuration

RS-232 interface. Only one interface can be enabled at a time.

GPIB interface is selected when the instrument is shipped from

Interface

1 Select the

GPIB (HPIB) interface.

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2 Select the GPIB address.

You can set the instrument’s address to any value between 0 and 30. The factory setting is address “9”.

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3 Save the change and exit the menu.

Note: Your computer’s GPIB interface card has its own address. Be sure to avoid using the computer’s address for any instrument on the interface bus. Agilent’s GPIB interface cards generally use address “21”.

Chapter 2 Front-Panel Overview

To Configure the Remote Interface

RS-232 Configuration

Interface

1 Select the RS -2 32 int erf a c e.

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2 Select the baud rate.

Select one of the following: 1200, 2400, 4800, 9600, 19200, 38400, 57600 (factory setting), or 115200 baud.

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3 Select the parity and number of data bits.

Select one of the following: None (8 data bits, factory setting), Even (7 data bits), or Odd (7 data bits). When you set the parity, you are also indirectly setting the number of data bits.

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Interface

4 Select the flow control method.

Select one of the following: None (no flow control),

XON/XOFF (factory setting), or Modem.

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5 Save the changes and ex it the menu.

RTS/CTS, DTR/DSR,

Chapter 2 Front-Panel Overview

To Store the Instrument State

You can store the instrument state in one o f five non-volatile storage locations. A sixth storage location automatically holds the power-down configuration of the instrument. When power is restored, the instrument can automatically return to its state before power-down (a scan in progress before power-down will also be resumed).

1 Select the storage location.

From the front panel, you have the ability to assign names (up to 12 characters) to each of the five stored states.

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The storage locations are numbered 1 through 5. The power-down state is automatically stored and can be recalled from the front panel (the state is named

LAST PWR DOWN).

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2 Store the instrument state.

The instrument stores all channel configurations, alarm values, scaling values, scan interval setups, and advanced measurement configurations.

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System Overview

This chapter provides an overview of a computer-based system and describes the parts of a data acquisition system. This chapter is divided into the following sections:

• Data Acquisition System Overview, see below

• Signal Routing and Switching, starting on page 57

• Measurement Input, starting on page 60

• Control Output, starting on page 67

Data Acquisition System Overview

You can use the Agilent 34970A as a stand-alone instrument but there are many applications where you will want to take advantage of t he built-i n connectivity features. A typical data acquisition system is shown below.

Computer and Software Interface Cable 34970A

Plug-in Modules

System Cabling

Transducers,

Sensors,

and Events

Chapter 3 System Overview

Data Acquisition System Overview

The system configuration shown on the previous page offers the following advantages:

• You can use the 34970A to perform data storage, data reduction,

mathematical calculations, and conversion to engineering units. You can use the

PC to provide easy configuration and data presentati on.

• You can remove the analog signals and measurement sensors from

the noisy

PC environment and electrically isolate them from both the

PC and earth ground.

• You can use a single PC to monitor multiple instruments and

The Computer and Interface Cable

Since computers and operating systems are the subject of many books and periodicals, they are not discussed in this chapter. In addition to the computer and operating system, you will need a serial port (

GPIB port (IEEE-488) and an interface cable.

Serial (RS-232) GPIB (IEEE-488)

Advantages Disadvantages Advantages Disadvantages

Often built into the computer; no additional hardware is required.

Drivers usually included in the operating system.

Cables readily available and inexpensive.

The 34970A is shipped with a serial cable (if internal DMM is ordered).

measurement points while performing other

Cable length is limited to 45 ft (15 m). *

Only one instrument or device can be connected per serial port.

Cabling is susceptible to noise, causing slow or lost communications.

Varying connector pinouts and styles.

Data transfers up to 85,000 characters/sec.

Speed; faster data and command transfers.

Additional system flexibility, multiple instruments can be connected to the same GPIB port.

Direct Memory Transfers are possible.

Data transfe r s up to 750,000 characters/sec.

PC-based tasks.

RS-232) or

Cable length is limited to 60 ft (20 m). *

Requires an expansion slot plug-in card in PC and associated drivers.

Requires special cable.

* You can overcome these cable length limitations using spe cia l communications hardware.

For example, you can use the Agilent E5810A LAN-to-GPIB Gateway interface or a serial modem.

Chapter 3 System Overview

Data Acquisition System Overview

Measurement Software

A variety of software is available to configure your data acquisition hardware and manipulate and display your measurement data.

Data Logging and Monitoring

Agilent BenchLink Data Logger is a Windows designed to make it easy to use the 34970A with your and analyzing measurements. The software is included with the 34970A when you order the internal

DMM. Use this software to set up your test,

acquire and archive measurement data, and perform real-time display and analysis of your incoming measurements.

-based application

PC for gathering

Agilent BenchLink Data Logger

Automated Testing with Multiple Instrumen ts

• Agilent VEE

• TransEra HTBASIC

• National Instruments LabVIEW

• Microsoft

Visual Basic or Visual C++

for Windows

Chapter 3 System Overview

Data Acquisition System Overview

The 34970A Data Acquisition / Switch Unit

As shown below, the logic circuitry for the 34970A is divided into two sections: earth-referenced and floating. These two sections are isolated from each other in order to maintain measurement accuracy and repeatability (for more information on ground loops, see page 341).

External Trigger

OUT IN

Alarms

To Computer

Optional

Digital Bus

Internal DMM

Analog Bus

100

200

300

Control

GPIB

RS-232

AC Power

Floating

Logic Earth Referenced Logic

= Optical Isolators

The earth-referenced and floating circuitry communicate with each other via an optically-isolated data link. The earth-referenced section communicates with the floating section to provide The instrument is shipped with both an

GPIB (IEEE-488) interface

PC connectivity.

and an RS-232 interface. Only one interface can be enabled at a time. The earth-referenced section also provides four hardware alarm outputs

and external trigger lines. You can use the alarm output lines to trigger external alarm lights, sirens, or send a

TTL pulse to your control system.

Plug-In Slots

The floating section contains the main system processor and controls all of the basic functionality of the instrument. Thi s is where the instrument communicates with the plug-in modules, scans the keyboard, controls the front-panel display, and controls the internal

DMM. The floating section

also performs Mx+B scaling, monitors alarm conditions, converts transducer measurements to engineering units, time stamps scanned measurements, and stores data in non-volatile memory.

Chapter 3 System Overview

Data Acquisition System Overview

Plug-In Modules

The 34970A offers a complete selection of plug-in modules to give you high-quality measurement, switching, and control capabilities. The plug-in modules communicate with the floating logic via the internal isolated digital bus. The multiplexer modules also connect to the internal microprocessor to offload the mainframe processor and minimize backplane communications for faster throughput. The table below shows some common uses for eac h plug-in module.

For more information on each module, refer to the module sections in chapter 4, starting on page 163.

Model Number Module Name Common Uses

34901A 20-Channel Mux with T/C

34902A 16-Channel Reed Mux with T/C

34908A 40-Channel Single-Ended Mux

34907A Multifunction Module Digital Input, Event Counting.

34901A 20-Channel Mux with T/C

34902A 16-Channel Reed Mux with T/C

34908A 40-Channel Single-Ended Mux

34904A 4x8 Matrix Switch 32 Crosspoint Matrix switching. 34905A 34906A

34903A 20-Channel Actuator General-purpose switching and control

34907A Multifunction Module Digital Output, Voltage (DAC) Outputs.

DMM via the internal analog bus. Each module has its own

Measurement Input

Compensation

with T/C Compensation

Signal Routing

Compensation

with T/C Compensation

Dual 4-Channel RF Mux (50 Dual 4-Channel RF Mux (75

Control Output

Scanning and direct measurement of temperature, voltage, resistance, frequency, and current (34901A only) using the internal DMM.

Scanning and direct measurement of temperature, voltage, and resistance using the internal DMM.

Multiplexing of signals to or from external instruments.

Ω) Ω)

Ω high-frequency applications (< 2 GHz).

using Form C (SPDT) switches.

Chapter 3 System Overview

Data Acquisition System Overview

System Cabling

The plug-in modules have screw-terminal connectors to make it easy to connect your system cabling. The type of cabling that you use to connect your signals, transducers, and sensors to the module is critical to measurement success. Some types of transducer s, such a s th ermocouples, have very specific requirements for the type of cable that can be used to make connections. Be sure to consider the usage environment when choosing wire gauge and insulation qualities. Wire insulation typically consists of materials such as

PVC or Teflon

several common cable types and describes their typical uses.

Note: Wiring insulation and usage is described in more detail in “System Cabling and Connections” starting on page 335.

Cable Type Common Uses Comments

Thermocouple Extension Wire

Twisted Pair, Shielded Twisted Pair

Shielded Coaxial, Double-Shielded Coaxial

Flat Ribbon, Twisted Pair Ribbon

Thermocouple measurements. Av ail a ble in s p ec ific th er mo couple types.

Measurement inputs, voltage outputs, switching, counting.

VHF signal switching. Most common cable for high-frequency

Digital Input/Output Often used with mass termination

. The table below lists

Also available in a shielded cable for added noise immunity.

Most common cable for low-frequency measurement inputs. Twisted pair reduces common mode noise. Shielded-twisted pair provides additional noise immunity.

signal routing. Available in specific impedance values (50 Provides excellent noise immunity. Double-shielded cable improves isolation between channels. Requires special connectors.

connectors. These cables provide little noise immunity.

Ω or 75Ω).

Teflon is a registered trademark of E.I. duPont deNemours and Company.

Chapter 3 System Overview

Data Acquisition System Overview

Transducers and Sensors

Transducers and sensors convert a physical quantity into an electrical quantity. The electrical quantity is measured and the result is then converted to engineering units. For example, when measuring a thermocouple, the instrument measures a dc voltage and ma themat icall y converts it to a corresponding temperature in

Measurement Typical Transducer Types Typical Transducer Output

Temperature Thermocouple 0 mV to 80 mV

RTD 2-wire or 4-wire resistance

Thermistor 2-wire resistance from

Pressure Solid State ±10 Vdc Flow Rotary Type

Thermal Type

Strain Resistive Elements 4-wire resistance from

Events Limit Switches

Optical Counters Rotary Encoder

Digital System Status TTL Levels

°C, °F, or K.

Ω to 500Ω

from 5

Ω to 1 MΩ

4 mA to 20 mA

Ω to 10 kΩ

10 0V or 5V Pulse Train

Alarm Limits

The 34970A has four alarm outputs which you can configure to alert you when a reading exceeds specified limits on a channel during a scan. You can assign a high limit, a low limit, or both to any configured channel in the scan list. You can assign multiple channels to any of the four available alarms (numbered 1 through 4). For example, you can configure the instrument to generate an alarm on Alarm 1 when a limit is exceeded on any of channels 103, 205, or 320.

You can also assign alarms to channels on the multifunction module. For example, you can generate an alarm when a specific bit pattern or bit pattern change is detec ted on a digi tal i np u t c h a nn e l or w he n a sp e ci fi c count is reached on a tota lizer c hannel . With th e multifu nct ion modul e, the channels do not have to be part of the scan list to generate an alarm.

Chapter 3 System Overview

Signal Routing and Switching

The switching capabilities of the plug-in modules available with the 34970A provide test system flexibility and expandability. You can use the switching plug-in modules to route signals to and from your test system or multiplex signals to the internal

Relays are electromechanical devices which are subject to wear-out failure modes . The life of a relay, or the number of actual operations before failure, is dependent upon how it is used – applied load, switching frequency, and environment. The 34970A Relay Maintenance System automatically counts the cycles of each relay in the instrument and stores the total count in non-volatile memory on each switch module. Use this feature to track relay fai lures and to p redict system main tenan ce requirements. For more information on using this feature, refer to

“Relay Cycle Count” on page 147.

Switching Topologies

DMM or external instruments.

Several switching plug-in modules are available with different topologies for various applications. The following switching topologies are available:

• Multiplexer (34901A, 34902A, 34905A, 34906A, 34908A)

• Matrix (34904A)

• Form C – Single Pole, Double Throw (34903A)

The following sections describe each of these switching topologies.

Chapter 3 System Overview

Signal Routing and Switching

Multiplexer Switching Multiplexers allow you to connect one of multiple channels to a common channel, one at a time. A simple 4-to-1 multiplexer is shown below. When you combine a multiplexer with a measurement device, like the internal

DMM, you create a scanner.

For more information on scanning, see page 62.

Channel 1

Common

Channel 2 Channel 3 Channel 4

Multiplexers are available in several types:

• One-Wire (Single-Ended) Multiplexers for common LO measurements.

For more information, see page 379.

• Two-Wire Multiplexers for floating measurements. For more

information, see page 379.

• Four-Wire Multiplexers for resistance and RTD measurements.

For more information, see page 380.

• Very High Frequency (VHF) Multiplexers for switching frequencies

up to 2.8 GHz. For more information, see page 390.

Chapter 3 System Overview

Signal Routing and Switching

Matrix Switching A matrix switch connects multiple inputs to multiple outputs and therefore offers more switching flexibility than a multiplexer. Use a ma trix for switc hing low- freq uenc y (less than 10 MHz) signals only. A matrix is arranged in rows and columns. For example, a simple 3x3 matrix could be used to connect three sources to three test points as shown below.

Source 1

NO = Normally Open NC = Normally Closed

Source 2

Source 3

Test 1 Test 2 Test 3

Any one of the signal sources can be connected to any one of the test inputs. Be aware that with a matrix, it is possible to connect more than one source at the same time. It is important t o make sure tha t dangerous or unwanted conditions are not created by these conn ections.

Form C (SPDT) Switching The 34903A Actuator contains 20 Form C switches (also called single-pole, double-throw). You can use Form C switches to route signals but they are typically used to control external devices.

Channel Open

(NC Contact Connected)

Channel Closed

(NO Contact Connected)

COM

Chapter 3 System Overview

Measurement Input

The 34970A allows you to combine a DMM (either internal or external) with multiplexe r c ha n nels to c reat e a scan. During a scan, the instrument connects the and makes a measurement on each channel.

Any channel that can be “read” by the instrument can also be included in a scan. This includes any combination of temperature, voltage, resistance, current, frequency, or period measurements on multiplexer channels. A scan can also include a read of a digital port or a read of the totalizer count on the multifunction module.

The Internal DMM

A transducer or sensor converts a physical quantity being measured into an electrical signal which can be measured by the internal To make these measurements, the internal following functions:

DMM to the configured multiplexer channels one at a time

DMM.

DMM incorporates the

• Temperature (thermocouple, RTD, and thermistor)

• Voltage (dc and ac up to 300V)

• Resistance (2-wire and 4-wire up to 100 MΩ)

• Current (dc and ac up to 1A)

• Frequency and Period (up to 300 kHz)

The internal

DMM provides a universal input front-end for measuring

a variety of transducer types without the need for additional external signal conditioning. The internal

DMM includes signal conditioning,

amplification (or attenuation), and a high resolution (up to 22 bits) analog-to-digital converter. A simplified diagram of the internal

DMM is

shown below.

Analog

Input

Signal

Conditioning

Amp

Analog to

Digital

Converter

Main

Processor

To / F rom Earth Referenced Section

= Optical Isolators

Chapter 3 System Overview

Measurement Input

Signal Conditioning, Ranging, and Amplification Analog input signals are multiplexed into the internal section – typically comprising switch ing , ranging, and amplification circuitry. If the input signal is a dc voltage, the signal conditioner is composed of an attenuator for the higher input voltages and a dc amplifier for the lower input voltages. If the input signal is an ac voltage, a converter is used to convert the ac signal to its equivalent dc value (true supplying a known dc current to an unknown resistance and measuring the dc voltage drop across the resistor. The input signal switching and ranging circuitry, together with the amplifier circuitry, convert the input to a dc voltage which is within the measuring range of the internal

You can allow the instrument to automatically select the measurement range using autoranging or you ca n select a fixed measurement range using manual ranging. Autoranging is convenient because the instrument automatically decides which range to use for each measurement based on the input signal. For fastest scanning operation, use manual ranging for each measurement (some additional time is required for autoranging since the instrument has to make a range selection).

RMS value). Resistance measurements are performed by

DMM’s analog-to-digital converter (ADC).

DMM’s signal-conditioning

Analog-to-Digi t al Conv er sion (ADC) The dc voltage from the signal-conditioning circuitry and converts it to digital data for output and display on the front panel. The the most basic measurement characteristics. These include measur eme nt resolution, reading speed , and the ab ilit y to reject spuriou s noise. There are several analog-to-digital conversion techniques but they can be divided into two types: integrating and non-integrating. The integrating techniques measure the average input value over a defined time interval, thus rejecting many noise sources. The non-integrating techniques sample the instantaneous value of the input, plus noise, during a very short interval. The internal

ADC technique.

You can select the resolution and reading speed from 6 digits (22 bits) at 3 readings per second to 4 digit s (16 bits) at up to 600 r eadi ngs per sec ond. The Advanced menu from the 34970A front panel allows you to control the integration period for precise rejection of noise signals.

ADC takes a prescaled

ADC governs some of

DMM uses an integrating

Chapter 3 System Overview

Measurement Input

Main Processor The main processor, located in the floating logic section, controls the input signal conditioning, ranging, and the The main processor accept s commands from, and sends measurement results to, the earth-referenced logic section. The main processor synchronizes measurements during scanning and control operations. The main processor uses a multi-tasking operating system to manage the various system resources and demands.

The main processor also calibrates measurement results, performs Mx+B scaling, monitors alarm conditions, converts transducer measurements to engineering units, time stamps scanned measurements, and stores data in non-volatile memory.

ADC.

Scanning

The instrument allows you to combine a DMM (either internal or external) with multiplexe r c ha n nels to c reat e a scan. During a scan, the instrument connects the and makes a measurement on each channel.

DMM to the configured multiplexer channels one at a time

Before you can initiate a scan, you must set up a scan list to include all desired multiplexer or digital channels. Channels which are not in the scan list are skipped during the scan. The instrument automatically scans the list of channels in ascending order from slot 100 through slot 300. Measurements are taken only during a scan and only on those channels which are included in the scan list.

You can store up to 50,000 readings in non-volatile memory during a scan. Readings are stored only during a scan and all readings are automatically time stamped. Each time you start a new scan, the instrument clears all readings stored in memory from the previous scan. Therefore, all readings currently stored in memory are from the most recent scan.

Chapter 3 System Overview

Measurement Input

You can configure the event or action that controls the onset of each sweep through the scan list (a sweep is one pass through the scan list):

• You can set the instrument’s internal timer to automatically scan at

a specific interval as shown below. You can also program a time delay between channels in the scan list.

Scan Count

(1 to 50,000 scans, or continuous)

Scan List (1 sweep)

Scan-to-Scan Interval

(0 to 99:59:59 hours)

• You can manually control a scan by repeatedly pressing from

the front panel.

• You can start a scan by sending a software command from the

remote interface.

• You can start a scan when an external TTL trigger pulse is received.

• You can start a scan when an alarm condition is logged on the

channel being monitored.

Chapter 3 System Overview

Measurement Input

Scanning With External Instruments

If your application doesn’t require the built-in measurement capabilities of the 34970A, you can order it without the internal configuration, you can use the 34970A for signal routing or control applications. If you install a multiplexer plug-in module, you can use the 34970A for scanning with an external instrument. You can connect an external instrument (such as a

H L

Input Channels

DMM) to the multiplexer COM terminal.

DMM. In this

External DMM

Common Terminals

(COM)

H L

To control scanning with an external instrument, two control lines are provided. When the 3497 0A an d t he ex te rnal i nstr um ent are p roper ly configured, you can synchronize a scan sequence between the two.

GND

Channel Closed OUT

34970A

Ext Trig IN

External DMM

VM Complete OUT Ext Trig IN

Chapter 3 System Overview

Measurement Input

The Multifunction Module

The multifunction modul e (34907 A) adds two additi onal measu rement input capabilities to the system: digital input and event totalize.

The multifunction module also contains a dual voltage output (DAC) which is described in more detail on page 68.

Digital Input The multifunction module has two non-isolated 8-bit input/output ports which you can use for reading digital patterns. You can read the live status of the bits on the port or you can configure a scan to include a digital read. Each port has a separate channel number on the module and contains 8-bits. You can combine the two ports to read a 16-bit word.

Bit 0

Port 1 (LSB) Channel 01

Digital

Input

Bit 7 Bit 0

Port 2 (MSB) Channel 02

Bit 7

Chapter 3 System Overview

Measurement Input

Totalizer The multifunction module has a 26-bit totalizer which can count pulses at a 100 kHz rate. You can manually read the totalizer count or you can configure a scan to read the count.

+IN

26 Bits

Totalize

-IN

Gate Gate

Channel 03

• You can configure the totalizer to count on the rising edge or falling

edge of the input signal.

• The maximum count is 67,108,863 (2

- 1). The count rolls over to “0”

after reaching the maximum allowed value.

• You can configure the totalizer to read without affecting the count or

reset the count to zero without losing any counts.

Chapter 3 System Overview

Control Output

In addition to signal routing and measurement, you can also use the 34970A to provide simple control outputs. For example, you can control external high-power relays using the a ctuator module or a digital output channel.

The Multifunction Module

The multifunction modu le (349 07A) add s two addi tional contr ol output capabilities to the syst em: di gital output and voltage (DAC) output.

The multifunction module also contains digital input and event totalizer capabilities which are described in more detail on pages 65 and 66.

Digital Output The multifunction module has two non-isolated 8-bit input/output ports which you can use to output digital patterns. Each port has a separate channel number on the module and contains 8-bits. You can combine the two ports to output a 16-bit word.

Bit 0

Digital

Output

Bit 7 Bit 0

Bit 7

Port 1 (LSB) Channel 01

Port 2 (MSB) Channel 02

Chapter 3 System Overview

Control Output

Voltage (DAC) Output The multifunction module has two analog outputs capable of outputting calibrated voltages between 16 bits of resolution. Each

DAC (Digital-to-Analog Converter) channel can

±12 volts with

be used as a programmable voltage source for analog input control of other devices. A simplified diagram is shown below.

DAC 1

DAC 2

Channel 04

Channel 05

• You can set the output voltage to any value between +12 Vdc and

-12 Vdc, in 1 mV steps. Each

DAC is earth referenced, it cannot float.

• Each DAC channel is capable of supplying 10 mA maximum current.

Note: You must limit the output current to 40 mA total for all three slots (six DAC channels).

Chapter 3 System Overview

Control Output

The Actuator / G eneral-Purpose Switch

You can think of the 34903A Actuator as a control output because it is often used to control external power devices. The actuator provides 20 independent, isolated Form C (

SPDT) switches.

NO = Normally Open NC = Normally Closed

Channel Open

(NC Contact Connected)

COM

Channel Closed

(NO Contact Connected)

COM

Each channel can switch up to 300V dc or ac rms. Each switch can also switch up to 1 A dc or ac rms up to 50 W maximum. For example, the maximum current that you can switch at 120 V is 0.45 A as shown below.

Voltage

Current

For control applications, the actuator has the following advantages:

• Higher voltage and power rating than the digital output channels.

The actuator switches can also be used to control power devices.

• When used with high-power devices, however, it is critical that you

provide protection to the switch from capacitive and inductive loads to ensure maximum relay life (for more information on attenuators, see the discussion on page 387).

Features and Functions

You will find that this chapter makes it easy to look up all the details about a particular feature of the 34970A. Whether you are operating the instrument from the front panel or over the remote interface, this chapter will be useful. This chapter is divided into the following sections:

• SCPI Language Conventions, on page 73

• Scanning, starting on page 74

• Single-Channel Monitoring, starting on page 93

• Scanning With External Instruments, starting on page 95

• General Measurement Configu ration, starting on page 98

• Temperature Measurement Configuration, starting on page 106

• Voltage Measurement Configuration, starting on page 113

• Resistance Measurement Configuration, on page 115

• Current Measurement Configuration, starting on page 116

• Frequency Measurement Configuration, starting on page 118

• Mx+B Scaling, starting on page 119

• Alarm Limits, starting on page 122

• Digital Input Operations, starting on page 133

• Totalizer Operations, starting on page 135

• Digital Output Operations, on page 138

• DAC Output Operations, on page 139

• System-Related Operations, starting on page 140

• Remote Interface Configuration, starting on page 150

• Calibration Overview, starting on page 155

• Factory Reset State, on page 160

• Instrument Preset State, on page 161

• Multiplexer Module Default Settings, on page 162

• Module Overview, on page 163

• 34901A 20-Channel Multiplexer, starting on page 164

• 34902A 16-Channel Multiplexer, starting on page 166

• 34903A 20-Channel Actuator, starting on page 168

• 34904A 4x8 Matrix Switch, starting on page 170

• 34905A/6A Dual 4-Channel RF Multiplexers, starting on page 172

• 34907A Multifunction Module, starting on page 174

• 34908A 40-Channel Single-Ended Multiplexer, starting on page 176

Chapter 4 Features and Functions

SCPI Language Conventions

Throughout this manual, the following conventions a re used for

SCPI command syntax for remote interface programming:

• Square brackets ( [ ] ) indicate optional keywords or parameters.

• Braces ( { } ) enclose paramete r choices within a command string.

• Triangle brackets ( < > ) enclose parameters for which you must

substitute a value.

• A vertical bar (

Rules for Using a Channel List

Many of th e SCPI commands for the 34970A include a scan_list or ch_list parameter which allow you to specify one or more channels. The channel number has the form ( (100, 200, or 300) and cc is the channel number. You can specify a single channel, multiple channels, or a range of channels as shown below.

) separates multiple parameter choices.

@scc), where s is the slot number

• The following command configures a scan list to include only

channel 10 on the module in slot 300.

ROUT:SCAN (

• The following command configures a scan list to include multiple

channels on the module in slot 200. The scan list now contains only channels 10, 12, and 15 (the scan list is redefined each time you send

a new ROUTe:SCAN command).

ROUT:SCAN (

• The following command configures a scan list to include a range of

channels. When you specify a range of channels, the range may contain invalid channels (they are ignored), but the first and last channel in the range must be valid. The scan list now contains channels 5 through 10 (slot 100) and channel 15 (slot 200).

ROUT:SCAN (

@310)

@210,212,215)

@105:110,215)

Chapter 4 Features and Functions

Scanning

• 34901A 20-Channel Multiplexer

• 34902A 16-Channel Multiplexer

• 34907A Multifunction Module (digital input and totalizer only)

• 34908A 40-Channel Single-Ended Multiplexer

Automated scanning is not allowed with th e ac t uat or mod ule, the matrix

module, or the include a write to a digital port or a voltage output from a However, you can write your own program to manually create a “scan” to include these operations.

DMM to the configured multiplexer channels one at a time

RF multiplexer modules. In addition, a scan cannot

DAC channel.

Rules for Scanning

• Before you can initiate a scan, you must set up a scan list to include

all desired multiplexer or digital channels. Channels which are not in the scan list are skipped during the scan. The instrument automatically scans the list of channels in ascending order from slot 100 through slot 300. Measurements are taken only during a scan and only on those channels which are included in the scan list. The “ ” (sample) annunciator turns on during each measurement.

• You can store up to 50,000 readings in non-volatile memory during

a scan. Readings are stored only during a scan and all readings are automatically time stamped. If memory overflows (the will turn on), a status register bit is set and new readings will overwrite the first readings stored (the most recent readings are always preserved). You can read the contents of memory at any time, even during a scan. Reading memory is not cleared when you read it.

MEM annunciator

Chapter 4 Features and Functions

Scanning

• Each time you start a new scan, the instrument clears all readings

(including alarm data) stored in reading memory from the previous scan. Therefore, the contents of memory are always from the most recent scan.

• While a scan is running, the instrument automatically stores the

minimum and maximum readings and calculates the average for each channel. You can read these values at any time, even during a scan.

• Mx+B scaling and alarm limits are applied to measurements during a

scan and all data is stored in non-volatile memory. You can read the contents of reading memory or the alarm queue at any time, even during a scan.

• In the Monitor function, the instrument takes readings as often as it

can on a single channel, even during a scan (see “Single-Channel Monitoring” on page 93). This feature is useful for troubleshooting

your system before a test or for watching an important signal.

• If you abort a scan that is running, the instrument will complete the

one measurement in progress (the entire scan will not be completed) and the scan will stop. You cannot resume the scan from where it left off. If you initiate a new scan, all readings are cleared from memory.

• When you add a multiplexer channel to a scan list, that entire module

is dedicated to the scan. The instrument issues a Card Reset to open all channels on that module. You cannot perform low-level close or open operations on any channels on that module (even those channels that are not configured).

• While a scan is running, you can perform some low-level control

operations on modules that do not contain channels in the scan list. For example, you can open or close channels or issue a Card Reset on switching modules that do not contain channels in the scan list. However, you cannot change any parameters that affect the scan (channel configuration, scan interval, scaling values, alarm limits, Card Reset, etc.) while a scan is running.

Chapter 4 Features and Functions

Scanning

• When you add a digital read (multifunction module) to a scan list,

that port is dedicated to the scan. The instrument issues a Card Reset to make that port an input port (the other port is not affected).

• While a scan is running, you can perform low-level control operations

on any channels on the multifunction module that are not in the scan. For example, you can output a

DAC voltage or write to a digital port

(even if the totalizer is part of the scan list). However, you cannot change any parameters that affect the scan (channel configuration, scan interval, Card Reset, etc.) while a scan is running.

• If a scan includes a read of the totalizer, multifunction module,

the count is reset each time it is read during the scan only when the totalizer reset mode is enabled (TOTalize:TYPE RRESet command or the Advanced menu for the totalizer).

• If you install a module while a scan is running, the instrument will

cycle power and resume scanning. If you remove a module while a scan is running, the instrument will cycle power and resume scanning (even if the removed module was part of the scan list).

• You can use either the internal DMM or an external DMM to make

measurements of your configured channels. However, the instrument allows only one scan list at a time; you cannot scan some channels using the internal Readings are stored in 34970A memory only when the internal

DMM and others using an external DMM.

DMM

is used.

• If the internal DMM is installed and enabled, the instrument will

automatically use it for scanning. For externally-controlled scans, you must either remove the internal

DMM from the 34970A

or disable it (see “Internal DMM Disable” on page 145).

Sweep 1: Sweep 2: Sweep 3:

Power Fails

Chapter 4 Features and Functions

Scanning

Power Failure

• When shipped from the factory, the instrument is configured to

automatically recall the power-down state when power is restored. In this configuration, the instrument will automatically recall the instrument state at power-down and resume a scan in progress. If you do not want the power-down state to be recalled when power is restored, send the MEMory:STATe:RECall:AUTO OFF command (also see the Utility menu); a Factory Reset (*R ST c om ma nd ) i s t h en issued when power is restored.

• If the instrument is in the middle of a scan sweep when power fails,

all readings from that partially completed sweep will be discarded (a sweep is one pass through the scan list). For example, assume that your scan list includes four multiplexer channels and you want to sweep through the scan list three times (see diagram). A power failure occurs after the second reading in the third scan sweep. The instrument will discard the last two of the 10 readings and will resume scanning at the beginning of the third scan sweep.

• If you remove a module or move a module to a different slot while

power is off, the scan will not resume when power is restored. No error is generated.

• If you replace a module with a module of the same type while power

is off, the instrument will continue scanning when power is restored. No error is generated.

Chapter 4 Features and Functions

Scanning

Adding Channels to a Scan List

Before you can initiate a scan, you must configure the channels to be scanned and set up a scan list (these two operations occur simultaneously from the front panel). The instrument automatically scans the configured channels in ascending order from slot 100 through slot 300.

To Build a Scan List From the Front Panel:

To add the active channel to the scan list, press . Select the function, range, resolution, and other measurement parameters for this

channel. You can also press to sequentially step through the scan list and take a measurement on each channel (readings are not stored in memory). This is an easy way to verify your wiring connections and channel configuration (also valid during a scan).

• When you reconfigure a channel and add it to the scan list, it is

important to note that the previous configuration on that channel is lost. For example, assume that a channel is configured for dc voltage measurements. When you reconfigure that channel for thermocouple measurements, the previous range, resolution, and channel delay are set to their Factory Reset (*RST command) state.

• To remove the active channel from the scan list, press and select

CHANNEL OFF. If you decide to add that channel back to the scan list

with the same function, the original channel configuration (including scaling and alarm values) is still present.

• To initiate a scan and store all readings in memory, press

SCAN annunciator will turn on). Each time you initiate a

(the new scan, the instrument clears all previously stored readings.

• To stop a scan, press and hold .

Chapter 4 Features and Functions

Scanning

To Build a Scan List From the Remote Interface:

• The MEASure?, CONFigure, and ROUTe:SCAN commands contain a

scan_list parameter which defines the list of channels in the scan list. Note that each time you send one of these commands, it redefines the scan list. To determine which channels are currently in the scan list, you can send the ROUTe:SCAN? query command.

• To initiate a scan, execute the MEASure?, READ?, or INITiate

command. The MEASure? and READ? commands send readings directly to the instrument’s output buffer but readings are not stored in memory. The INITiate command stores readings in memory. Use the FETCh? command to retrieve stored readings from memory.

See the examples starting on page 201 in chapter 5 for more information on using these commands.

• When you reconfigure a channel and add it to the scan list using

MEASure? or CONFigure, it is important to note that the previous configuration on that channel is lost. For example, assume that a channel is configured for dc voltage measurements. When you reconfigure that channel for thermocouple measurements, the previous range, resolution, and channel delay are set to their Factory Reset (*RST command) state.

• Each time you initiate a new scan, the instrument clears all

previously stored readings.

• To stop a scan, execute the ABORt command.

Chapter 4 Features and Functions

Scanning

Scan Interval

You can configure the event or action that controls the onset of each sweep through the scan list (a sweep is one pass through the scan list):

• You can set the instrument’s internal timer to automatically scan at a

specific interval. You can also program a time delay between channels in the scan list.

• You can manually control a scan by repeatedly pressing from

the front panel.

• You can start a scan by sending a software command from the

remote interface (MEASure? or INITiate command).

• You can start a scan when an external TTL trigger pulse is received.

• You can start a scan when an alarm event is logged on the channel

being monitored.

Interval Scanning In this configuration, you control the frequency of scan sweeps by selecting a wait period from the start of one sweep to the start of the next sweep (called the scan-to-scan interval). The countdown time is shown on the front-panel display between one scan sweep and the start of the next sweep. If the scan interval is less than the time required to measure all channels in the scan list, the instrument will scan continuously, as fast as possible (no error is generated).

(1 to 50,000 scans, or continuous)

Scan Count

Scan List (1 sweep)

Scan-to-Scan Interval

(0 to 99:59:59 hours)

Chapter 4 Features and Functions

Scanning

• You can set the scan interval to any value between 0 seconds

and 99:59:59 hours (359,999 seconds), with 1 ms resolution.

• Once you have initiated the scan, the instrument will continue

scanning until you stop it or until the scan count is reached.

See “Scan Count” on page 86 for more information.

• Mx+B scaling and alarm limits are applied to measurements during

a scan and all data is stored in non-volatile memory.

• The MEASure? and CONFigure commands automatically set the

scan interval to immediate (0 seconds) and the scan count to 1 sweep.

• From the front panel, a Factory Reset (Sto/Rcl menu) sets the scan

interval to 10 seconds and the scan count to continuous. From the remote interface, a Factory Reset (*RST command) sets the scan interval to immediate (0 seconds) and the scan count to 1 sweep.

• Front-Panel Operation: To select interval scanning and set a scan

interval time (hour:minutes:seconds), choose the following item.

INTERVAL SCAN

To initiate the scan and store all readings in memory, press (the

SCAN annunciator will turn on). Between scan sweeps,

the count-down time is shown on the front-panel (00:04 TO SCAN). Note: To stop a scan, press and hold .

• Remote Interface Operation: The following program segment

configures the instrument for an interval scan.

TRIG:SOURCE TIMER Select the interval timer configuration TRIG:TIMER 5 Set the scan interval to 5 seconds TRIG:COUNT 2 Sweep the scan list 2 times INIT Initiate the scan

Note: To stop a scan, send the ABORt command.

Chapter 4 Features and Functions

Scanning

Scan Once In this configuration, the instrument waits for either a front-panel key press or a remote interface command before sweeping through the scan list.

• All readings from the scan are stored in non-volatile memory.

Readings accumulate in memory until the scan is terminated (until the scan count is reached or until you abort the scan).

• You can specify a scan count which sets the number of front-panel

key presses or scan trigger commands that will be accepted before terminating the scan. See “Scan Count” on page 86 for more

information.

• Mx+B scaling and alarm limits are applied to measurements during

a Scan Once operation and all data is stored in non-volatile memory.

• Front-Panel Operation:

MANUAL SCAN

To initiate the scan and store all readings in memory, press . The

ONCE annunciator turns on as a reminder that a Scan Once

operation is in progress. Note: To stop a scan, press and hold .

• Remote Interface Operation: The following program segment

configures the instrument for a Scan Once operation.

TRIG:SOURCE BUS Select the bus (once) configuration TRIG:COUNT 2 Sweep the scan list 2 times INIT Initiate the scan

Then, send the *TRG (trigger) command to begin each scan sweep. You can also trigger the instrument from the sending the

IEEE-488 Group Execute Trigger (GET) message.

GPIB interface by

The following statement shows how to send a GET message. TRIGGER 709 Group Execute Trigger Note: To stop a scan, send the ABORt command.

Chapter 4 Features and Functions

Scanning

External Scanning In this configuration, the instrument sweeps through the scan list once each time a low-going on the rear-panel Ext Trig Input line (pin 6).

TTL pulse is received

Ext Trig Connector

5 V 0 V

Ext Trig Input

Gnd

Input

> 1 µs

• You can specify a scan count which sets the number of external

pulses the instrument will accept before terminating the scan.

See “Scan Count” on page 86 for more information.

• If the instrument receives an external trigger before it is ready to

accept one, it will buffer one trigger before generating an error.

• All readings from the scan are stored in non-volatile memory.

Readings accumulate in memory until the scan is terminated (until the scan count is reached or until you abort the scan).

• Mx+B scaling and alarm limits are applied to measurements during

the scan and all data is stored in non-volatile memory.

• Front-Panel Operation:

EXTERNAL SCAN

To initiate the scan, press . The reminder that an External Scan is in progress. When a received, the scan starts and readings are stored in memory. To stop

a scan, press and hold .

• Remote Interface Operation: The following program segment

configures the instrument for an External Scan.

TRIG:SOURCE EXT Select the external trigger configuration TRIG:COUNT 2 Sweep the scan list 2 times INIT Initiate the scan

Note: To stop a scan, send the ABORt command.

EXT annunciator turns on as a

TTL pulse is

Chapter 4 Features and Functions

Scanning

Scanning on Alarm In this configuration, the instrument sweeps the scan list once each time a reading crossing an alarm limit on a channel. You can also assign alarms to channels on the multifunction module. For example, you can generate an alarm when a specific bit pattern is detected or when a specific count is reached.

Note: For complete details on configuring and using alarms, refer to “Alarm Limits” starting on page 122.

• In this scan configuration, you may use the Monitor function to

continuously take readings on a selected channel and wait for an alarm on that channel. The monitored channel can be part of the scan list but you can also use a channel on the multifunction module (which does not have to be part of the scan list and you do not have to use the Monitor function). For example, you can generate an alarm on a totalizer channel which will initiate a scan when a specific count is reached.

• You can specify a scan count which sets the number of alarms that

will be allowed before terminating the scan. See “Scan Count” on page 86 for more information.

• All readings from the scan are stored in non-volatile memory.

Readings accumulate in memory until the scan is terminated (until the scan count is reached or until you abort the scan).

• Mx+B scaling and alarm limits are applied to measurements during

the scan and all data is stored in non-volatile memory.

• Front-Panel Operation:

SCAN ON ALARM

To enable the Monitor function select the desired channel and then press . To initiate the scan, press . When an alarm event

occurs, the scan starts and readings are stored in memory. Note: To stop a scan, press and hold .

Chapter 4 Features and Functions

Scanning

• Remote Interface Operation: The following program segment configures

the instrument to scan when an alarm occurs.

TRIG:SOURCE ALARM1 Select the alarm configuration TRIG:COUNT 2 Sweep the scan list 2 times

CALC:LIM:UPPER 5,( CALC:LIM:UPPER:STATE ON,( OUTPUT:ALARM1:SOURCE (

ROUT:MON ( ROUT:MON:STATE ON Enable monitoring

INIT Initiate the scan Note: To stop a scan, send the ABORt command.

@103) Select monitor channel

@103) Set the upper limit

@103) Enable the upper limit

@103) Report alarms on Alarm 1

Chapter 4 Features and Functions

Scanning

Scan Count

You can specify the number of times the instrument will sweep through the scan list. When the specified number of sweeps have occurred, the scan stops.

• Select a scan count between 1 to 50,000 scan sweeps, or continuous.

• During an Interval Scan (see page 80), the scan count sets the number

of times the instrument will sweep through the scan list and therefore determines the overall duration of the scan.

• During a Scan Once operation (see page 82), the scan count sets the

number of front-panel key presses or scan trigger commands that will be accepted before terminating the scan.

• During an External Scan (see page 83), the scan count sets the

number of external trigger pulses that will be accepted before terminating the scan.

• During an Alarm Scan (see page 84), the scan count sets the number

of alarms that will be allowed before terminating the scan.

• You can store up to 50,000 readings in non-volatile memory during

a scan. If you set a continuous scan and memory overflows (the annunciator will turn on), a status register bit is set and new readings will overwrite the first readings stored (the most recent readings are always preserved).

MEM

• The MEASure? and CONFigure commands automatically set the

scan count to 1.

• From the front panel, a Factory Reset (Sto/Rcl menu) sets the scan

count to continuous. From the remote interface, a Factory Reset (*RST command) sets the scan count to 1 sweep.

• Front-Panel Operation:

00020 SCANS

The default is 1 and 50,000 scans, turn the knob clockwise and enter a number.

• Remote Interface Operation:

TRIG:COUNT 20

Note: To configure a continuous scan, send TRIG:COUNT INFINITY.

CONTINUOUS. To set the count to a value between

Chapter 4 Features and Functions

Scanning

Reading Format

During a scan, the instrument automatically adds a time stamp to all readings and stores them in non-volatile memory. Each reading is stored with measurement units, time stamp, channel number, and alarm status information. From the remote interface, you can specify which information you want returned with the readings (from the front panel, all of the information is available for viewing). The reading format applies to all readings being removed from the instrument from a scan; you cannot set the format on a per-channel basis.

• From the remote interface, the time stamp information is returned

either in absolute time (time of day with date) or relative time (time since start of scan). Use the FORMat:READ:TIME:TYPE command to select absolute or relative time. From the front panel, the time stamp is always returned in absolute time.

• The MEASure? and CONFigure commands automatically turn off the

units, time, channel, and alarm information.

• A Factory Reset (*RST command) turns off the units, time, channel,

and alarm information.

• Remote Interface Operation: The following commands select the

format of readings returned from a scan.

FORMat:READing:ALARm ON FORMat:READing:CHANnel ON FORMat:READing:TIME ON FORMat:READing:TIME:TYPE {ABSolute|RELative} FORMat:READing:UNIT ON

The following is an example of a reading stored in memory with all fields enabled (relative time is shown).

1 Reading with Units (26.195 °C)

2 Time Since Start of Scan (17 ms)

3 Channel Number

4 Alarm Limit Threshold Crossed

(0 = No Alarm, 1 = LO, 2 = HI)

Chapter 4 Features and Functions

Scanning

Channel Delay

You can control the pace of a scan sweep by inserting a delay between multiplexer channels in the scan list (useful for high-impedance or high-capacitance circuits). The delay is inserted between the relay closure and the actual measurement on the channel. The programmed channel delay overrides the default channel delay that the instrument automatically adds to each channel.

Scan List

Ch 1 Ch 2 Ch 3 Ch 4 Ch 5 Ch 6

Channel Delay

• You can set the channel delay to any value between 0 seconds and

60 seconds, with 1 ms resolution. You can select a different delay for each channel. The default channel delay is automatic; the instrument determines the delay based on function, range, integration time, and ac filter setting (see “Automatic Channel Delays” on the next page).

• The MEASure? and CONFigure commands set the channel delay

to automatic. A Factory Reset (*RST command) also sets the channel delay to automatic.

• Front-Panel Operation:

CH DELAY TIME

• Remote Interface Operation: The following command adds a 2-second

channel delay to channel 101.

ROUT:CHAN:DELAY 2,(

@101)

Chapter 4 Features and Functions

Scanning

Automatic Channel Delays

If you do not specify a channel delay, the instrument selects a delay for you. The delay is determined by function, range, integration time, and ac filter setting as shown below.

DC Voltage, Thermocouple, DC Current (for all ranges):

Integration Time Channel Delay

PLC > 1

PLC

≤ 1

Resistance, RTD, Thermistor ( 2- and 4-wire):

2.0 ms

1.0 ms

Range

100

1 kΩ

10 kΩ

100 kΩ

1 MΩ

10 MΩ

100 MΩ

Channel Delay

(For PLC > 1)

Ω

2.0 ms

2.0 ms 25 ms 30 ms

200 ms 200 ms

Range

Ω

100

1 kΩ

10 kΩ

100 kΩ

1 MΩ

10 MΩ

100 MΩ

AC Voltage, AC Current (for all ranges):

AC Filter Channel Delay

Slow (3 Hz)

Medium (20 Hz)

Fast (200 Hz)

7.0 sec

1.0 sec 120 ms

Frequency, Period:

AC Filter Channel Delay

Slow (3 Hz)

Medium (20 Hz)

Fast (200 Hz)

0.6 sec

0.3 sec

0.1 sec

Digital Input, Totaliz e:

Channel Delay

0 sec

Channel Delay

(For PLC

≤ 1)

1.0 ms

1.0 ms 20 ms 25 ms

200 ms 200 ms

Chapter 4 Features and Functions

Scanning

• Front-Panel Operation:

CH DELAY AUTO

• Remote Interface Operation: The following command enables an

automatic channel delay on channel 01.

ROUT:CHAN:DELAY:AUTO ON,(

@101)

Selecting a specific channel delay using the ROUTe:CHANnel:DELay command disables the automatic channel delay.

Viewing Readings Stored in Me mory

During a scan, the instrument automatically adds a time stamp to all readings and stores them in non-volatile memory. Readings are stored only during a scan. You can read the contents of memory at any time, even during a scan.

• You can store up to 50,000 readings in non-volatile memory during

a scan. From the front panel, you can view the last 100 readings and all of the readings are available from the remote interface. If memory overflows (the is set and new readings will overwrite the first readings stored (the most recent readings are always preserved).

• Each time you start a new scan, the instrument clears all readings

(including alarm data) stored in reading memory from the previous scan. Therefore, the contents of memory are always from the most recent scan.

• The instrument clears all readings in memory after a Factory Reset

(*RST command) or Instrument Preset (SYSTem:PRESet command). Reading memory is not cleared when you read it.

MEM annunciator will turn on), a status register bit

• While a scan is running, the instrument automatically stores the

minimum and maximum readings and calculates the average for each channel. You can read these values at any time, even during a scan.

• Each reading is stored with measurement units, time stamp, channel

number, and alarm status information. From the remote interface, you can specify which information you want returned with the readings (from the front panel, all of the information is available for viewing). For more information, see “Reading Format” on page 87.

Chapter 4 Features and Functions

Scanning

• Readings acquired during a Monitor are not stored in memory

(however, all readings from a scan in progress at the same time are stored in memory).

• The MEASure? and READ? commands send readings directly to the

instrument’s output buffer but readings are not stored in memory. You will not be able to view these readings.

• The INITiate command stores readings in memory. Use the FETCh?

command to retrieve stored readings from memory (the readings are not erased when you read them).

• Front-Panel Operation: From the front panel, data is available for

the last 100 readings on each channel readings taken during a scan (all of the data is available from the remote interface). After turning

the knob to the desired channel, press the and keys to choose the data that you w ant t o vi ew for the selec t ed ch an nel as sh own b elow (the

LAST, MIN, MAX, and AVG annunciators turn on to indicate what

data is currently being viewed). Reading memory is not cleared when you read it. Note that you can view readings from the front panel even while the instrument is in remote.

READINGS

and

Select Channel Last Reading on Channel

99th Most Recent Reading on Channel

Chapter 4 Features and Functions

Scanning

• Remote Interface Operation: The following command retrieves stored

readings from memory (the readings are not erased).

FETCH?

Use the following commands to query the statistics on the readings stored in memory for a specific channel. These commands do not remove the data from memory.

CALC:AVER:MIN? ( CALC:AVER:MIN:TIME? (

CALC:AVER:MAX? ( CALC:AVER:MAX:TIME? (

CALC:AVER:AVER? (

CALC:AVER:COUNT? (

CALC:AVER:PTPEAK? (

@305) Minimum reading on channel

@305) Time minimum was logged

@305) Maximum reading on channel

@305) Time maximum was logged

@305) Average of all readings on channel

@305) Number of readings taken on channel

@305) Peak-to-peak (maximum-minimum)

The following command retrieves the last reading taken on channel 301 during a scan.

DATA:LAST? (

@301)

The following command clears the contents of statistics memory for the selected channel.

CALC:AVER:CLEAR (

@305)

Use the following command to determine the total number of readings stored in memory (all channels) from the most recent scan.

DATA:POINTS?

The following command reads and clears the specified number of readings from memory. This allows you to continue a scan without losing data stored in memory (if memory becomes full, new readings will overwrite the first readings stored). The specified number of readings are cleared from memory, starting with the oldest reading.

DATA:REMOVE? 12

Chapter 4 Features and Functions

Single-Channel Monitoring

In the Monitor function, the instrument takes readings as often as it can on a single channel, even during a scan. This feature is useful for troubleshooting your system before a test or for watching an important signal.

Any channel that can be “read” by the instrument can be monitored. This includes any combination of temperature, voltage, resistance, current, frequency, or period measurements o n multiplexer channels. You can also monitor a digital input port or the totalizer count on the multifunction module. Monitoring is not allowed with the actuator module, the matrix module, or the

• The Monitor function is equivalent to making continuous

measurements on a single channel with an infinite scan count. Only one channel can be monitored at a time but you can change the channel being monitored at any time.

• Readings acquired during a Monitor are not stored in memory but

they are displayed on the front panel (however, all readings from a scan in progress at the same time are stored in memory).

RF multiplexer modules.

• Mx+B scaling and alarm limits are applied to the selected channel

during a Monitor and all alarm data is stored in the alarm queue (which will be cleared if power fails).

• A scan in progress always has priority over the Monitor function.

The instrument will take at least one monitor reading per scan sweep and will take more as time permits.

• You can monitor a multiplexer channel only if the internal DMM is

installed and enabled (see “Internal DMM Disable” on page 145). The channel must also be configured to be part of the scan list.

• You can monitor a digital input channel or totalizer channel even if

the channel is not part of the scan list (the internal required either). The count on a totalizer channel is not reset when it is being monitored (the Monitor ignores the totalizer reset mode).

DMM is not

Chapter 4 Features and Functions

Single-Channel Monitoring

• In the Alarm Scan configuration (see “Scanning on Alarm” on page 84),

the instrument sweeps the scan list once each time a reading crosses an alarm limit on a channel. In this configuration, you may use the Monitor function to continuously take readings on a selected channel and wait for an alarm on that channel. The monitored channel can be part of the scan list but you can also use a cha nnel on t he multifunction module (which does not have to be part of the scan list and you do not have to use the Monitor function).

• Front-Panel Operation: To start a Monitor, press . Turn the

knob to advance to the desired channel. The instrument begins monitoring after you pause for a few seconds on a configured channe l.

To stop a Monitor, press again. Note that while the instrument in in the remote mode, you can still turn on the Monitor function and select the desired channel.

• Remote Interface Operation: The following program segment selects

the channel to be monitored (specify only one channel) and enables the Monitor function.

ROUT:MON (

@101)

ROUT:MON:STATE ON

To read the monitor data from the selected channel, send the following command. This command returns the reading only; the units, time, channel, and alarm information are not returned (the FORMat:READing commands do not apply to monitor readings).

ROUT:MON:DATA?

Chapter 4 Features and Functions

Scanning With External Instruments

If your application doesn’t require the built-in measurement capabilities of the 34970A, you can order it without the internal configuration, you can use the system for signal routing or control applications. If you install a multiplexer plug-in module, you can use the system for scanning with an external instrument. You can connect an external instrument (such as a

Input Channels

DMM) to the multiplexer COM terminal.

Common Terminals

(COM)

H L

DMM. In this

External DMM

To control scanning with an external instrument, two control lines are provided. When the 3497 0A an d t he ex te rnal i nstr um ent are p rop erly configured, you can synchronize a scan sequence between the two.

GND

Channel Closed OUT

34970A

Ext Trig IN

External DMM

VM Complete OUT Ext Trig IN

Chapter 4 Features and Functions

Scanning With External Instruments

In this configuration, you must set up a scan list to include all desired multiplexer or digital channels. Channels which are not in the list are skipped during the scan. The instrument automatically scans the list of channels in ascending order from slot 100 through slot 300.

For an externally-controlled scan, you must either remove the internal

DMM from the 34970A or disable it (see “Internal DMM Disable” on

page 145). Since the internal DMM is not used, readings from multiplexer channels are not stored in internal reading memory.

External connections are required to synchronize the scan sequence between the 34970A and the external instrument. The 34970A must notify the external instrument when a relay is closed and settled (including channel delay). The 34970A outputs a Channel Closed pulse from pin 5 on the rear-panel connector (see previous page). In response, the external instrument must notify the 34970A when it has finished its measurement and is ready to advance to the next channel in the scan list. The 34970A accepts a Channel Advance signal on the External Trigger input line (pin 6).

• You can configure the event or action that controls the onset of each

sweep through the scan list (a sweep is one pass through the scan list). When the internal

DMM is removed (or disabled), the default scan

interval source is “timer”. For more information, refer to “Scan Interval”

on page 80.

• You can configure the event or action that notifies the 34970A to

advance to the next channel in the scan list. Note that the Channel Advance source shares the same sources as the sc an interval.

However, an error is generated if you attempt to set the channel advance source to the same source used for the scan interval.

• You can specify the number of times the instrument will sweep

through the scan list. When the specified number of sweeps have occurred, the scan stops. For more information, refer to “Scan Count”

on page 86.

Chapter 4 Features and Functions

Scanning With External Instruments

• An externally-controlled scan can also include a read of a digital port

or a read of the totalizer count on the multifunction module. When the channel advance reaches the first digital channel, the instrument scans through all of the digital channels in that slot and stores the readings in reading memory (only one channel advance signal is required).

• You can configure the list of channels for 4-wire external scanning

without the internal automatically pairs channel n with channel n+10 (34901A) or n+8 (34902A) to provide the source and sense connections.

• Front-Panel Operation: To select the channel advance source, choose

from the following items.

AUTO ADVANCE , EXT ADVANCE

DMM. When enabled, the instrument

To initiate the scan, press (the To configure the instrument for 4-wire external scanning, choose the

following item.

4W SCAN

• Remote Interface Operation: The following program segment

configures the instrument for an externally-controlled scan.

TRIG:SOUR TIMER Select the scan interval ROUT:CHAN:ADV:SOUR EXT Select the channel advance source TRIG:TIMER 5 Set the scan interval to 5 seconds TRIG:COUNT 2 Sweep the scan list 2 times INIT Initiate the scan

To configure the instrument for 4-wire external scanning, send the following command.

ROUTe:CHANnel:FWIRe {OFF|ON}[,(

SCAN annunciator will turn on).

@<ch_list>)]

Chapter 4 Features and Functions

General Measurement Configuration

This section contains general information to help you configure the instrument for making measurements during a scan. Since these parameters are used by several measurement functions, the discussion is combined into one common section. Refer to the later sections in this chapter for more information on parameters that are specific to a particular measurement function.

Note: It is important that you select the measurement function before selecting other parameters on a given channel. When you ch ange the function on a chan nel, all other settings (range, resolution, etc.) are reset to their default values.

Measurement Range

You can allow the instrument to automatically select the measurement range using autoranging or you can select a fixed range using manual ranging. Autoranging is convenient because the instrument decides which range to use for each measurement based on the input signal. For fastest scanning operation, use manual ranging on each measurement (some additional time is required for autoranging since the instrument has to make a range selection).

• Autorange thresholds:

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

• If the input signal is greater than can be measured on the selected

range, the instrument gives an overload indication: “ the front panel or “

• For a complete list of the measurement ranges available for each

function, refer to the instrument specifications in chapter 9.

• For temperature measurements, the instrument internally selects

the range; you cannot select which range is used. For thermocouple measurements, the instrument internally selects the 100 mV range. For thermistor and to the correct range for the transducer resistance measurement.

±9.90000000E+37” from the remote interface.

RTD measurements, the instrument autoranges

±OVLD” from

Agilent Technologies 34970A User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual