Racal Instruments 3151 User manual

User Manual
3151/3151A
WAVEFORM GENERATOR
Publication No. 980768
RACAL INSTRUMENTS
Racal Instruments, Inc.
4 Goodyear St., Irvine, CA 92618-2002
Tel: (800) RACAL-ATE, [phone], [phone]; FAX: [phone]
Racal Instruments, Ltd.
480 Bath Road, Slough, Berkshire, SL1 6BE, United Kingdom
Tel: [phone]; FAX: [phone]
Racal Systems Electronique S.A.
18 Avenue Dutartre, 78150 LeChesnay, France
Tel: [phone]; FAX: [phone]
Racal Systems Elettronica s.r.l.
Strada 2-Palazzo C4, 20090 Milanofiori Assago, Milan, Italy
Tel: [phone]; FAX [phone]
Racal Elektronik System GmbH.
Technologiepark Bergisch Gladbach, Friedrich-Ebert-Strasse, D-51429 Bergisch Gladbach, Germany
Tel.: [phone]; FAX: [phone]
Racal Australia Pty. Ltd.
3 Powells Road, Brookvale, NSW 2100, Australia
Tel: [phone], FAX: [phone]
Racal Electronics Pte. Ltd.
26 Ayer Rajah Crescent, 04-06/07 Ayer Rajah Industrial Estate, Singapore 0513.
Tel: [phone], FAX: [phone]
Racal Instruments, Ltd.
Unit 5, 25F., Mega Trade Center, No 1, Mei Wan Road, Tsuen Wan, Hong Kong, PRC
Tel: [phone], FAX: [phone]
http://www.racalinstruments.com
PUBLICATION DATE: July 25, 2000
Copyright 2000 by Racal Instruments, Inc. Printed in the United States of America. All rights reserved.
This book or parts thereof may not be reproduced in any form without written permission of the publisher.

WARRANTY STATEMENT
All Racal Instruments, Inc. products are designed and manufactured to exacting standards and in full
conformance to Racal’s ISO 9001 procedures.
For the specific terms of your standard warranty, or optional extended warranty or service agreement, contact
your Racal customer service advisor. Please have the following information available to facilitate service.
1. Product serial number
2. Product model number
3. Your company and contact information
You may contact your customer service advisor by:
E-Mail: [email protected]
Telephone: [phone] (USA)
[phone] (UK)
[phone] (Hong Kong)
Fax: [phone] (USA)
[phone] (UK)
[phone] (Hong Kong)
RETURN of PRODUCT
Authorization is required from Racal Instruments before you send us your product for service or calibration. Call
your nearest Racal Instruments support facility. A list is located on the last page of this manual. If you are
unsure where to call, contact Racal Instruments, Inc. Customer Support Department in Irvine, California, USA at
1-800-722-3262 or 1-949-859-8999 or via fax at 1-949-859-7139. We can be reached at:
[email protected].
PROPRIETARY NOTICE
This document and the technical data herein disclosed, are proprietary to Racal Instruments, and shall not,
without express written permission of Racal Instruments, be used, in whole or in part to solicit quotations from a
competitive source or used for manufacture by anyone other than Racal Instruments. The information herein has
been developed at private expense, and may only be used for operation and maintenance reference purposes or
for purposes of engineering evaluation and incorporation into technical specifications and other documents which
specify procurement of products from Racal Instruments.

FOR YOUR SAFETY
Before undertaking any troubleshooting, maintenance or exploratory procedure, read carefully the
WARNINGS and CAUTION notices.
This equipment contains voltage hazardous to human life and safety, and is capable of inflicting
personal injury.
If this instrument is to be powered from the AC line (mains) through an autotransformer, ensure the
common connector is connected to the neutral (earth pole) of the power supply.
Before operating the unit, ensure the conductor (green wire) is connected to the ground (earth)
conductor of the power outlet. Do not use a two-conductor extension cord or a three-prong/two-
prong adapter. This will defeat the protective feature of the third conductor in the power cord.
Maintenance and calibration procedures sometimes call for operation of the unit with power applied
and protective covers removed. Read the procedures and heed warnings to avoid “live” circuit
points.
Before operating this instrument:
1. Ensure the instrument is configured to operate on the voltage at the power source. See
Installation Section.
2. Ensure the proper fuse is in place for the power source to operate.
3. Ensure all other devices connected to or in proximity to this instrument are properly grounded or
connected to the protective third-wire earth ground.
If the instrument:
-fails to operate satisfactory
-shows visible damage
-has been stored under unfavorable conditions
-has sustained stress
Do not operate until performance is checked by qualified personnel.

This page was left intentionally blank.

3151 And 3151A User Manual
i
Table of Contents
Chapter 1
Getting Started..................................................................................................................................1-1
What’s In This Chapter ..................................................................................................................1-1
Introduction.....................................................................................................................................1-1
Options...........................................................................................................................................1-3
Manual Changes............................................................................................................................1-4
Safety Considerations....................................................................................................................1-4
Supplied Accessories.....................................................................................................................1-5
Specifications.................................................................................................................................1-5
Functional Description....................................................................................................................1-5
Input and Output Connectors.....................................................................................................1-5
Main Output.............................................................................................................................1-5
SYNC Output ..........................................................................................................................1-6
External Clock Input................................................................................................................1-6
Reference Clock Output .........................................................................................................1-6
Trigger Input............................................................................................................................1-6
Operating Modes........................................................................................................................1-7
Continuous Mode....................................................................................................................1-7
Triggered Mode.......................................................................................................................1-7
Burst Mode..............................................................................................................................1-7
Gated Mode ............................................................................................................................1-8
Output Type................................................................................................................................1-8
Standard Waveforms..............................................................................................................1-8
Arbitrary Waveforms...............................................................................................................1-8
Sequenced Waveforms..........................................................................................................1-8
Output State..............................................................................................................................1-10
Synchronization ........................................................................................................................1-10
Filter..........................................................................................................................................1-10
Front Panel Indicators ..............................................................................................................1-11
Programming The Model 3151/3151A.........................................................................................1-11
Chapter 2

3151 And 3151A User Manual
ii
Configuring The Instrument..............................................................................................................2-1
Installation Overview......................................................................................................................2-1
Unpacking and Initial Inspection.................................................................................................2-1
Safety Precautions.........................................................................................................................2-1
Performance Checks......................................................................................................................2-2
Grounding Requirements ...........................................................................................................2-2
Long Term Storage or Repackaging For Shipment...................................................................2-3
Preparation For Use.......................................................................................................................2-3
Logical Address Selection..........................................................................................................2-4
Installation...............................................................................................................................2-6
Chapter 3
Using The Instrument .......................................................................................................................3-1
Overview.........................................................................................................................................3-1
Output Termination.....................................................................................................................3-1
Input/Output Protection...............................................................................................................3-1
Power On/Reset Defaults...........................................................................................................3-1
What To Do Now............................................................................................................................3-2
Using the APPLy Command ..........................................................................................................3-3
Output Configuration Commands ..................................................................................................3-8
Selecting an Output Function Type............................................................................................3-8
Selecting a Standard Function Shape........................................................................................3-8
Changing the Frequency and Sample Clock..............................................................................3-9
Selecting the Sample Clock Source.........................................................................................3-10
Programming the Output Amplitude and Offset.......................................................................3-10
Selecting the Filter Type...........................................................................................................3-11
Activating the Backplane ECLTRG and TTLTRG....................................................................3-12
Assigning the Validating Source For TTLTRG.....................................................................3-13
Enabling the Main Output.........................................................................................................3-13
Enabling the Sync Output.........................................................................................................3-14
Assigning the Source For The SYNC Output.......................................................................3-14
Selecting the SYNC Position ................................................................................................3-15
Using the Built-In Standard Waveforms...................................................................................3-16
Selecting an Operating Mode.......................................................................................................3-19
Triggered Mode ........................................................................................................................3-19

3151 And 3151A User Manual
iii
Gated Mode..............................................................................................................................3-19
Burst Mode................................................................................................................................3-20
Selecting the Trigger Source........................................................................................................3-21
Using the Internal Trigger Generator........................................................................................3-22
Selecting the Trigger Slope..........................................................................................................3-23
Using the Soft Trigger..................................................................................................................3-23
Generating Arbitrary Waveforms .................................................................................................3-24
What Are Arbitrary Waveforms? ..............................................................................................3-24
Arbitrary Memory Management................................................................................................3-24
Memory Management Commands...........................................................................................3-24
Loading Arbitrary Waveforms...................................................................................................3-26
Reversing Byte Order............................................................................................................3-28
Using Shared Memory ..........................................................................................................3-28
Sequence..................................................................................................................................3-30
Generating Sequenced Waveforms.............................................................................................3-31
What Are Sequenced Waveforms?..........................................................................................3-31
Sequence Commands..............................................................................................................3-33
High Speed Sequence Downloads (3151A Only)....................................................................3-35
Triggered Sequence Advance..................................................................................................3-37
Triggered Sequence Advance Commands..............................................................................3-38
Inter-Module Synchronization.......................................................................................................3-39
Synchronization............................................................................................................................3-39
Amplitude Modulation Commands ...........................................................................................3-41
System-Related Commands.....................................................................................................3-42
Chapter 4
SCPI Command Reference..............................................................................................................4-1
What’s In This Chapter ..................................................................................................................4-1
Introduction To SCPI Language.....................................................................................................4-1
Command Format.......................................................................................................................4-2
Command Separator..................................................................................................................4-3
The MIN and MAX Parameters...............................................................................................4-3
Querying Parameter Setting.......................................................................................................4-4
Query Response Format.........................................................................................................4-4
SCPI Command Terminator.......................................................................................................4-4

3151 And 3151A User Manual
iv
IEEE-STD-488.2 Common Commands.........................................................................................4-4
SCPI Parameter Type.................................................................................................................4-5
Numeric Parameters...............................................................................................................4-5
Discrete Parameters...............................................................................................................4-5
Boolean Parameters...............................................................................................................4-5
Arbitrary Block Parameters.....................................................................................................4-6
SCPI Command Summary.........................................................................................................4-6
Output Configuration Command Summary................................................................................4-9
Standard Waveform Command Summary...............................................................................4-11
Arbitrary Waveform, Sequence, and Shared Memory Command Summary...........................4-12
Modulation Command Summary..............................................................................................4-12
Trigger CommandSummary.....................................................................................................4-13
Inter-Module Phase Synchronization Command Summary.....................................................4-13
System-Related Command Summary......................................................................................4-14
IEEE-STD-488.2 Common Commands and Queries ..............................................................4-14
The SCPI Status Registers.......................................................................................................4-16
The Status Byte Register (STB)...............................................................................................4-18
Reading the Status Byte Register.........................................................................................4-18
Clearing the Status Byte Register.........................................................................................4-19
Service Request Enable Register (SRE)..............................................................................4-19
Standard Event Status Register (ESR) ................................................................................4-20
Standard Event Status Enable Register (ESE)....................................................................4-21
Error Messages............................................................................................................................4-21
Device-Specific Commands.........................................................................................................4-23
Chapter 5..........................................................................................................................................5-1
Maintenance and Performance Checks...........................................................................................5-1
What’s in This Chapter...................................................................................................................5-1
Disassembly Instructions............................................................................................................5-1
Special Handling of Static Sensitive Devices.............................................................................5-2
Cleaning......................................................................................................................................5-2
Repair and Replacement............................................................................................................5-3
Performance Checks..................................................................................................................5-3
Environmental Conditions.......................................................................................................5-4
Warm-Up Period.....................................................................................................................5-4

3151 And 3151A User Manual
v
Initial Instrument Setting .........................................................................................................5-4
Recommended Test Equipment.............................................................................................5-5
Performance Check Procedures................................................................................................5-5
Frequency Accuracy ...............................................................................................................5-6
Amplitude Accuracy ................................................................................................................5-7
DC Offset Characteristics.......................................................................................................5-8
Squarewave Characteristics...................................................................................................5-9
Sine Characteristics..............................................................................................................5-10
Sine Flatness ........................................................................................................................5-11
Trig, Gate and Burst Characteristics ....................................................................................5-12
Adjustments..............................................................................................................................5-14
Environmental Conditions.....................................................................................................5-14
Warm-Up Period...................................................................................................................5-14
Recommended Test Equipment...........................................................................................5-14
Adjustment Procedures.........................................................................................................5-14
Pulse Response Adjustment.................................................................................................5-15
Amplitude Adjustment...........................................................................................................5-16
Offset Adjustment .................................................................................................................5-17
Troubleshooting............................................................................................................................5-18
Recommended Test Equipment...............................................................................................5-18
Power-Up Tests........................................................................................................................5-18
Self-Test....................................................................................................................................5-18
Main Board Circuit Checkout....................................................................................................5-19
Power Supply Checkout ...........................................................................................................5-19
CPU and VXI ASIC Checkout...................................................................................................5-20
Output Amplifier and Amplitude Control Checkout ..................................................................5-21
Clock Synthesizer Checkout.....................................................................................................5-22
Sequence Generator Checks...................................................................................................5-23
Engine Board Circuit Checkout................................................................................................5-24
Engine Board Checkout........................................................................................................5-24
Chapter 6
OPTIONAL HARNESS ASSEMBLIES.............................................................................................6-1
Chapter 7
PRODUCT SUPPORT .....................................................................................................................7-1

3151 And 3151A User Manual
vi
Product Support .............................................................................................................................7-1
Reshipment Instructions.................................................................................................................7-1
Support Offices...............................................................................................................................7-2
Appendix A
Specifications...................................................................................................................................A-1

3151 And 3151A User Manual
vii
List of Figures
Figure 1-1, 3151 and 3151A Front Panel..........................................................................................1-2
Figure 1-2, Segment 1 - Sin(x)/x Waveform......................................................................................1-9
Figure 1-3, Segment 2 - Sine Waveform...........................................................................................1-9
Figure 1-4, Segment 3 - Pulse Waveform.........................................................................................1-9
Figure 1-5, Sequenced Waveforms.................................................................................................1-10
Figure 2-1, Set The Logical Address.................................................................................................2-5
Figure 3-1, Definite Length Arbitrary Block Data Format ................................................................3-27
Figure 3-2, 12-Bit Waveform Data Format......................................................................................3-28
Figure 3-3, Sin(x)/x Waveform Loaded Into Segment 1..................................................................3-31
Figure 3-4, Sine Waveform Loaded Into Segment 2.......................................................................3-32
Figure 3-5, Pulse Waveform Loaded Into Segment 3.....................................................................3-32
Figure 3-6, Sequenced Waveforms - Continuous Advance Mode..................................................3-33
Figure 3-7, Fast Sequence Download.............................................................................................3-36
Figure 3-8, Sequenced Waveforms - Triggered Advance Mode ....................................................3-38
Figure 4-1, SCPI Status Registers...................................................................................................4-17

3151 And 3151A User Manual
viii
List of Tables
Table 3-1, Default Conditions After Power On, RESet or *RST........................................................3-2
Table 3-2, Amplitude and Offset Ranges..........................................................................................3-3
Table 5-1, CPU and VXI Interface Checkout Procedure.................................................................5-20
Table 5-2, Output Amplifier and Amplitude Control Checkout Procedure ......................................5-21
Table 5-3, Clock Synthesizer Checkout Procedure.........................................................................5-22
Table 5-4, Sequence Generator Checkout Procedure....................................................................5-23
Table 5-5, Burst Generator Checks.................................................................................................5-24
Table 5-6b, Engine Board Checkout Procedure - #2......................................................................5-26
Table 5-6c, Engine Board Checkout Checkout Procedure - #3......................................................5-26

3151 And 3151A User Manual
Getting Started 1-1
Chapter 1
Getting Started
What’s In This
Chapter This chapter contains a general description of the VXIbus Model
3151/3151A Waveform Generator and an overall functional
description of the instrument. It lists and describes various options
available for this model. It also describes the Model 3151/3151A
front panel connectors and indicators.
NOTE
The Model 3151A is fully hardware and software
compatible with the Model 3151. It may replace any 3151
module. Any features mentioned in this manual are
compatible with both models except where stated
otherwise..
Introduction A detailed functional description is given following the general
description of the features, functions, and options available with the
Model 3151/3151A.
The Model 3151/3151A is a VXIbus, single slot C-size module.
Waveform Generator. It is a high performance waveform generator
that combines two powerful instruments in one small package; a
function generator and an arbitrary waveform generator. The
instrument provides a variety of standard waveforms to be used as
test stimuli for different electronic devices. The Model 3151/3151A is
also capable of generating arbitrary waveforms with sampling rates to
100 MHz at 12 bits of vertical resolution.
Despite its small size, the Model 3151/3151A offers many features
and functions such as VXIplug&play compatibility, phase
synchronization, counted burst, internal trigger-generator, and more.
The instrument generates high quality, high accuracy waveforms
throughout the specified frequency range, amplitude span, and
operating temperature.
The Model 3151/3151A generates standard waveforms at
frequencies ranging from 100 mHz to 50 MHz. Arbitrary waveforms
are generated with clock rates ranging from 100 µHz to 100 MHz.
Output amplitude may be programmed within the range of 20 mV to

3151 And 3151A User Manual
Getting Started 1-2
32 Vp-p into an open circuit, and 10 mV to 16V into 50Ω.
Figure 1-1, 3151 and 3151A Front Panel

3151 And 3151A User Manual
Getting Started 1-3
Besides its normal continuous mode, the Model 3151/3151A offers a
variety of interrupted modes. The output waveform may be gated,
triggered, or may generate a counted burst of waveforms. A built-in
trigger generator with a programmable period can replace an
external trigger.
The Model 3151/3151A generates arbitrary waveforms with 12 bits of
resolution. There are nine standard waveforms which are memory-
resident. Other waveforms may be generated, either manually or
downloaded from the controller to the instrument using shared
memory or standard data bus transfer. Waveforms may also be
generated using the WaveCAD program.
The Model 3151A waveform generator is a digital instrument.
Besides its standard waveforms, any waveform it generates must first
be loaded into the arbitrary waveform memory. The arbitrary
waveform memory is a bank of 8-bit words. Each word represents a
point on the waveform. Each word has a horizontal address that can
range from 0 to 523288 (64536 for the Model 3151) and a vertical
address that can range from -2047 to +2048 (12 bits). Using a high
speed clocking circuit, the digital contents of the arbitrary waveform
memory are extracted and routed to the D/A converter. The D/A
converts the digital data to an analog signal, and the output amplifier
completes the task by amplifying or attenuating the signal at the
output connector.
The Model 3151/3151A is fully programmable using SCPI commands
and syntax. There are two ways to program the Model 3151/3151A,
the first being low level programming of each individual parameter.
The second alternative is to use the VXIplug&play driver for high
level programming. The VXIplug&play driver simulates a mechanical
front panel with the necessary push buttons, displays and dials to
operate the Model 3151/3151A as a bench-top instrument. The
Model 3151/3151A will not operate without being programmed.
Therefore, it is recommended that the user become familiar with its
basic features, functions and programming concepts as described in
this and the following chapters.
Options A number of options are offered with the Model 3151/3151A.
Compare the option number with the number that is printed on the
instrument to verify which of the options is installed in your
instrument. Note that all Model 3151/3151A options are installed in
the factory. Contact your nearest Racal representative if the number
printed on the case does not reflect the correct version ordered. The
list of available Model 3151/3151A options is given below:
•407719-002 - Model 3151A - 100MS/s Waveform Generator,
w/512k RAM
•407719-012 - Model 3151A - 100MS/s Waveform Generator,

3151 And 3151A User Manual
Getting Started 1-4
w/512k RAM, 1PPM
•407382-001 - Model 3151 - 100MS/s Waveform Generator,
w/64k RAM
•407382-011 - Model 3151 - 100MS/s Waveform Generator,
w/512k RAM
•407382-021 - Model 3151 - 100MS/s Waveform Generator,
w/64k RAM, 1PPM
•407382-002 - Model 3151 - 100MS/s Waveform Generator,
w/512k RAM, 1PPM
•407382-012 - Model 3151 - 100MS/s Waveform Generator, w/
64k RAM, 100PPM
•407382-021 - Model 3151 - 100MS/s Waveform Generator,
w/512k RAM, 100PPM
The Model 3151A is supplied with 512k of waveform memory
allowing 523288 point waveforms to be programmed. The 3151-001
version has 64536 points available.
1ppm option denotes an improved accuracy and stability of the 10
MHz reference clock. Normally, VXI modules receive their clock
reference from VXIbus CLK10. There are applications that require
complete separation from VXI clocks. The crystal oscillator TCXO
(1ppm) option, when installed, provides this separation.
Manual Changes Technical corrections to this manual (if any) are listed in the back of
this manual on an enclosed MANUAL CHANGES sheet.
Safety
Considerations The Model 3151/3151A has been manufactured according to
international safety standards. The instrument meets VDE
0411/03.81 and UL 1244 standards for safety of commercial
electronic measuring and test equipment for instruments with an
exposed metal chassis that is directly connected to earth via the
chassis power supply cable.

3151 And 3151A User Manual
Getting Started 1-5
WARNING
Do not remove instrument covers when operating or
when the chassis power cord is connected to the mains.
Any adjustment, maintenance and repair of an opened, powered-on
instrument should be avoided as much as possible, but when
necessary, should be carried out only by a skilled person who is
aware of the hazard involved.
Supplied
Accessories
The Model 3151/3151A is supplied with an Instruction Manual. The
manual includes disks with VXIplug&play drivers along with
WaveCAD for Windows. A Service Manual is available upon
request.
Specifications Instrument specifications are listed in Appendix A. These
specifications are the performance standards or limits against which
the instrument is tested. Specifications apply under the following
conditions: output terminated into 50Ωafter 30 minutes of warm-up
time, and within a temperature range of 20oC to 30oC. Specifications
outside this range are degraded by 0.1% per oC.
Functional
Description
A detailed functional description is given in the following paragraphs.
The description is divided into logical groups: input and output
connectors, operating modes, output type, output state,
synchronization, filters and front panel indicators.
Input and Output
Connectors
The Model 3151/3151A has 5 BNC connectors on its front panel:
main output, SYNC output, external clock input, reference clock
output and the trigger input.
Main Output The main output connector outputs standard, user, and sequenced
waveforms. Output impedance of this output is 50Ω, that is, the
cable which is connected to this input should be terminated with a
50Ωresistance. Output amplitude accuracy is calibrated when
connected to a 50Ωload. If the output is connected to a different load
resistance, determine the actual amplitude from the resistance ratio
of the internal 50Ωto the load impedance. The output amplitude is
doubled when the output impedance is above 1 MΩ.

3151 And 3151A User Manual
Getting Started 1-6
SYNC Output The SYNC output generates a single TTL pulse for synchronizing
other instruments (i.e., an oscilloscope) to the output waveform. The
SYNC signal always appears at a fixed point relative to the
waveform. The SYNC output generates a single point pulse for
standard and arbitrary waveforms. The location of the SYNC signal
along the waveform is programmable from point 2 to the last point on
the waveform.
External Clock Input The external clock input is available for those applications required to
run the complete system off the same clock. Normally, this input is
disabled. When enabled, the clock at this input replaces the internal
clock generator and the output waveform will begin generating
waveforms with clock rates that are present at the external clock
input. Do not confuse the clock frequency with the frequency of the
waveform. The actual frequency of the output waveform depends on
the number of points that are allocated for the waveform. For
example, if the external clock is 10 MHz and the number of points
that were assigned to the active segment is 1000, the output
frequency will be 10 kHz (10 MHz divided by the number of points).
The external clock input accepts fixed level TTL signals within the
range of DC to 100 MHz.
Reference Clock
Output The reference clock output is a 10 MHz fixed level TTL signal that is
derived directly from the internal 10 MHz reference crystal. This
output may serve as a reference clock to other instruments or
devices that require a 10 MHz clock synchronization signal.
Trigger Input The trigger input accepts signals that stimulate the Model
3151/3151A to output waveforms. The trigger input is inactive when
the instrument is in continuous operating mode. When placed in
trigger, gated or burst mode, the trigger input is made active and
waits for the right condition to trigger the instrument. In trigger and
burst modes, the trigger input is edge sensitive, i.e., it senses
transitions from high to low or from low to high to trigger the Model
3151/3151A. The direction of the transition is programmable. The
trigger input accepts fixed level TTL signals.
In gated mode, the trigger input is level sensitive, i.e., the Model
3151/3151A is gated when the level is high and idle when the level is
low. Level sensitivity may be programmed for the trigger input.

3151 And 3151A User Manual
Getting Started 1-7
Operating Modes There are a number of operating modes that the Model 3151/3151A
can be programmed to operate in: continuous mode, triggered mode,
gated mode and burst mode. These operating modes are described
below.
Continuous Mode In continuous mode, the selected waveform is output continuously at
the selected frequency, amplitude and offset.
Triggered Mode In triggered mode, the Model 3151/3151A circuits are armed to
generate one output waveform. The trigger circuit is sensitive to
transitions at the trigger input. Select between positive or negative
transitions to trigger the instrument. When triggered, the generator
outputs the waveform and remains idle at the last point of the
waveform. The Model 3151/3151A can be armed to receive a trigger
signal from a front panel BNC connector, a VXI backplane
TTLTRG<n> or from an internal, programmable trigger generator.
The trigger signal, whether it comes from the front panel or from the
VXIbus, has to pass through some circuits. These circuits cause a
small delay known as system delay. System delay cannot be
eliminated completely. It is, however, minimized in the Model
3151/3151A to approximately 200ns maximum. System delay is a
factor that must be considered when applying a trigger signal. It
defines how long it will take from a valid trigger edge to the moment
that the output reacts.
While system delay cannot be controlled, the Model 3151/3151A
offers a controllable trigger delay parameter. When utilized, delay
from trigger signal to output waveform may be programmed from 0
clocks to one Million clocks. This delay is additional to the system
delay.
Burst Mode The burst mode is an extension of the triggered mode where the
Model 3151/3151A can be armed to output a counted number of
waveforms following a triggered signal. Like trigger mode, burst can
be triggered from a front panel BNC connector, a VXI backplane
TTLTRG<n> or from an internal, programmable trigger generator.

3151 And 3151A User Manual
Getting Started 1-8
Gated Mode In gated mode, the Model 3151/3151A circuits are armed to generate
output waveforms as long as a gating signal is true. Unlike the
triggered mode, the gated mode is level sensitive. When the gating
signal goes false, the waveform at the output connector is first
completed and the output goes to an idle state. The stop amplitude
level, after a gating signal, is the last point on the waveform.
Output Type The Model 3151/3151A can output three types of waveforms:
standard waveforms, arbitrary waveforms and sequenced
waveforms. The three types of waveforms are described in the
following.
Standard
Waveforms The Model 3151A generates waveforms from a memory that has to
be loaded before the instrument can generate waveforms. There are
512k points of memory. 1k points from this memory are allocated for
standard waveforms. Waveforms are loaded into this part of the
memory each time a standard function is selected.
The Model 3151/3151A can be programmed to output nine different
standard waveforms: sine wave, triangular wave, square wave,
pulse, ramp, sinc (sine(x)/x), pulse, gaussian pulse, exponential
pulse and DC. There are certain parameters that are associated with
each standard function. These parameters can be programmed to
generate modified standard waveforms.
Arbitrary Waveforms The arbitrary waveform memory is capable of storing one or more
user waveforms. There are 523288 points that can be allocated to
one waveform that has this length. If there is no need to use the
complete memory, it can be divided into smaller segments, variable
in size. Load each segment with a different waveform and program
the Model 3151A to output the required waveform for a specific test.
Loading data to arbitrary waveform memory can be a time consuming
task, especially if the complete 512K is loaded in one shot. The
Model 3151A utilizes the VXIbus shared memory concept that
speeds data transfer from and to the host computer. In this mode,
the memory bank is disconnected from the CPU circuit and its bus is
accessible from the VXIbus for direct memory access by the host
computer.
Sequenced
Waveforms The Model 3151/3151A employs a sophisticated circuit that allows
dividing the memory into smaller segments, linking of the segments
in user-defined order, and repeating of each linked segment up to