National Instruments GPIB-BUF User manual

© Copyright 1989, 1994 National Instruments Corporation.
All Rights Reserved.
GPIB-BUF
User Manual
February 1994 Edition
Part Number 320125-01

National Instruments Corporate Headquarters
6504 Bridge Point Parkway
Austin, TX 78730-5039
[phone]
Technical support fax: [phone]
[phone]
Branch Offices:
Australia [phone], Austria [phone], Belgium 02/757.00.20,
Canada (Ontario) [phone], Canada (Québec) [phone],
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Germany 089/741 31 30, Italy 02/48301892, Japan [phone],
Netherlands 03480-33466, Norway 32-848400, Spain (91) 640 0085,
Sweden 08-730 49 70, Switzerland 056/20 51 51, U.K. 0635 523545

MicroGPIB Products
National Instruments has developed the MicroGPIB product line to offer a
series of high performance, low cost IEEE 488 support items that are
packaged in small all-metal cases, capable of being rack mounted.
Limited Warranty
The GPIB-BUF is warranted against defects in materials and workmanship
for a period of two years from the date of shipment, as evidenced by
receipts or other documentation. National Instruments will, at its option,
repair or replace equipment that proves to be defective during the warranty
period. This warranty includes parts and labor.
A Return Material Authorization (RMA) number must be obtained from the
factory and clearly marked on the outside of the package before any
equipment will be accepted for warranty work. National Instruments will
pay the shipping costs of returning to the owner parts which are covered by
warranty.
National Instruments believes that the information in this manual is
accurate. The document has been carefully reviewed for technical accuracy.
In the event that technical or typographical errors exist, National
Instruments reserves the right to make changes to subsequent editions of
this document without prior notice to holders of this edition. The reader
should consult National Instruments if errors are suspected. In no event
shall National Instruments be liable for any damages arising out of or
related to this document or the information contained in it.
EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO
WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS
ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES
CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL
INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE
PAID BY THE CUSTOMER. NATIONAL INSTRUMENTS WILL NOT BE
LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA, PROFITS,
USE OF PRODUCTS, OR INCIDENTAL OR CONSEQUENTIAL DAMAGES,
EVEN IF ADVISED OF THE POSSIBILITY THEREOF. This limitation of the
liability of National Instruments will apply regardless of the form of action,
whether in contract or tort, including negligence. Any action against
National Instruments must be brought within one year after the cause of

action accrues. National Instruments shall not be liable for any delay in
performance due to causes beyond its reasonable control. The warranty
provided herein does not cover damages, defects, malfunctions, or service
failures caused by owner’s failure to follow the National Instruments
installation, operation, or maintenance instructions; owner’s modification of
the product; owner’s abuse, misuse, or negligent acts; and power failure or
surges, fire, flood, accident, actions of third parties, or other events outside
reasonable control.
Copyright
Under the copyright laws, this publication may not be reproduced or
transmitted in any form, electronic or mechanical, including photocopying,
recording, storing in an information retrieval system, or translating, in
whole or in part, without the prior written consent of National Instruments
Corporation.
Trademarks
MicroGPIB® is a trademark of National Instruments Corporation.
Product and company names listed are trademarks or trade names of their
respective companies.
Warning Regarding Medical and Clinical Use
of National Instruments Products
National Instruments products are not designed with components and testing
intended to ensure a level of reliability suitable for use in treatment and
diagnosis of humans. Applications of National Instruments products
involving medical or clinical treatment can create a potential for accidental
injury caused by product failure, or by errors on the part of the user or
application designer. Any use or application of National Instruments
products for or involving medical or clinical treatment must be performed by
properly trained and qualified medical personnel, and all traditional medical
safeguards, equipment, and procedures that are appropriate in the particular
situation to prevent serious injury or death should always continue to be
used when National Instruments products are being used. National
Instruments products are NOT intended to be a substitute for any form of
established process, procedure, or equipment used to monitor or safeguard
human health and safety in medical or clinical treatment.

FCC/DOC Radio Frequency
Interference Compliance
This equipment generates and uses radio frequency energy and, if not
installed and used in strict accordance with the instructions in this manual,
may cause interference to radio and television reception. This equipment
has been tested and found to comply with the following two regulatory
agencies:
Federal Communications Commission
This device complies with Part 15 of the Federal Communications
Commission (FCC) Rules for a Class A digital device. Operation is subject
to the following two conditions:
1. This device may not cause harmful interference in commercial
environments.
2. This device must accept any interference received, including
interference that may cause undesired operation.
Canadian Department of Communications
This device complies with the limits for radio noise emissions from digital
apparatus set out in the Radio Interference Regulations of the Canadian
Department of Communications (DOC).
Le présent appareil numérique n’émet pas de bruits radioélectriques
dépassant les limites applicables aux appareils numériques de classe A
prescrites dans le règlement sur le brouillage radioélectrique édicté par le
ministère des communications du Canada.
Instructions to Users
These regulations are designed to provide reasonable protection against
harmful interference from the equipment to radio reception in commercial
areas. Operation of this equipment in a residential area is likely to cause
harmful interference, in which case the user will be required to correct the
interference at his own expense.

There is no guarantee that interference will not occur in a particular
installation. However, the chances of interference are much less if the
equipment is installed and used according to this instruction manual.
If the equipment does cause interference to radio or television reception,
which can be determined by turning the equipment on and off, one or more
of the following suggestions may reduce or eliminate the problem.
• Operate the equipment and the receiver on different branches of your
AC electrical system.
• Move the equipment away from the receiver with which it is interfering.
• Reorient or relocate the receiver’s antenna.
• Be sure that the equipment is plugged into a grounded outlet and that
the grounding has not been defeated with a cheater plug.
Notice to user: Changes or modifications not expressly approved by
National Instruments could void the user’s authority to
operate the equipment under the FCC Rules.
If necessary, consult National Instruments or an experienced radio/television
technician for additional suggestions. The following booklet prepared by
the FCC may also be helpful: How to Identify and Resolve Radio-TV
Interference Problems. This booklet is available from the U.S. Government
Printing Office, Washington, DC 20402, Stock Number 004-000-00345-4.

© National Instruments Corp. vii GPIB-BUF User Manual
Contents
About This Manual ..........................................................................ix
Introduction to the GPIB-BUF ...................................................ix
Organization of This Manual......................................................ix
Conventions Used in This Manual .............................................x
Related Documentation ..............................................................x
Customer Communication ..........................................................x
Chapter 1
Description of the GPIB-BUF......................................................1-1
Introduction.................................................................................1-1
What Your Kit Contains.............................................................1-2
Optional Equipment....................................................................1-2
The GPIB-BUF Front Panel .......................................................1-3
The GPIB-BUF Rear Panel ........................................................1-4
The GPIB Connectors.................................................................1-4
Chapter 2
Installation and Operation .................................................2-1
Installation ..................................................................................2-2
Step 1. Inspect the GPIB-BUF...................................2-2
Step 2. Verify the Voltage Requirement....................2-2
Step 3. Configure the Operating Parameters .............2-3
Set Configuration Switches ...........................2-4
Step 4. Connect the Cables ........................................2-6
Step 5. Power on the Unit ..........................................2-7
Operation ....................................................................................2-7
Chapter 3
Technical Information ....................................................................3-1
Power Up ....................................................................................3-1
Addressing ..................................................................................3-2
Data Transfers.............................................................................3-2
EOI .............................................................................................3-3
IFC ..............................................................................................3-4
REN ............................................................................................3-4
Polling the GPIB-BUF ...............................................................3-5
Special Note About Timeouts.....................................................3-8
Multiline Command Group.........................................................3-8

Contents
GPIB-BUF User Manual viii © National Instruments Corp.
Appendix A
Hardware Specifications..............................................................A-1
Appendix B
Customer Communication..........................................................B-1
Glossary...............................................................................................G-1
Figures
Figure 1-1. The GPIB-BUF ...................................................................1-1
Figure 1-2. The GPIB-BUF Front Panel ................................................1-3
Figure 1-3. The GPIB-BUF Rear Panel .................................................1-4
Figure 1-4. The GPIB Connector and Signal Designations ...................1-5
Figure 2-1. GPIB-BUF System Setup Example.....................................2-1
Figure 2-2. Factory Default Switch Settings..........................................2-4
Figure 3-1. Serial Poll Status Byte.........................................................3-5
Tables
Table 1-1. LED Descriptions ................................................................1-3
Table 2-1. Configuration Parameters for Switches 1 through 3 ...........2-4
Table 2-2. Configuration Parameters for Switches 4 through 8 ...........2-5
Table 3-1. Parallel Poll Responses .......................................................3-7
Table A-1. Electrical Characteristics.....................................................A-1
Table A-2. Environmental Characteristics.............................................A-1
Table A-3. Physical Characteristics.......................................................A-2

© National Instruments Corp. ix GPIB-BUF User Manual
About This Manual
Introduction to the GPIB-BUF
The GPIB-BUF is one of National Instruments family of MicroGPIB
products. These products are high-performance, low-cost IEEE 488
support items, packaged in small all-metal cases, capable of being rack
mounted.
Organization of This Manual
This manual is organized as follows:
• Chapter 1, Description of the GPIB-BUF, contains general information
about the National Instruments GPIB-BUF and lists components and
accessories.
• Chapter 2, Installation and Operation, describes the procedures for
installing and operating the GPIB-BUF.
• Chapter 3, Technical Information, contains a more detailed description
of the operation of the GPIB-BUF. The timing characteristics of the
parallel port are provided in this chapter.
• Appendix A, Hardware Specifications, contains tables which specify
the electrical, environmental, and physical characteristics of the
GPIB-BUF.
• Appendix B, Customer Communication, contains forms you can use to
request help from National Instruments or to comment on our products
and manuals.
• The Glossary contains an alphabetical list and a description of terms
used in this manual, including abbreviations, acronyms, metric
prefixes, mnemonics, and symbols.

About This Manual
GPIB-BUF User Manual x © National Instruments Corp.
Conventions Used in This Manual
The following conventions are used in this manual.
italic Italic text denotes emphasis, a cross reference,
or an introduction to a key concept.
bold italic Bold italic text denotes a note, caution, or
warning.
bold Bold text denotes the name of light-emitting
diode (LED).
Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms
are listed in the Glossary.
Related Documentation
The following document contains information that you may find helpful as
you read this manual.
• ANSI/IEEE Standard 488.1-1987, IEEE Standard Digital Interface for
Programmable Instrumentation
• ANSI/IEEE Standard 488.2-1987, IEEE Standard Codes, Formats,
Protocols, and Common Commands.
Customer Communication
National Instruments wants to receive your comments on our products and
manuals. We are interested in the applications you develop with our
products, and we want to help if you have problems with them. To make it
easy for you to contact us, this manual contains comment and configuration
forms for you to complete. These forms are in Appendix B, Customer
Communication, at the end of this manual.

© National Instruments Corp. 1-1 GPIB-BUF User Manual
Chapter 1
Description of the GPIB-BUF
This chapter contains general information about the National Instruments
GPIB-BUF and lists components and accessories.
Introduction
The GPIB-BUF, shown in Figure 1-1, is an IEEE 488 (GPIB) data buffer
which increases GPIB performance by isolating a slow GPIB data acceptor
from the rest of the GPIB system. This increase in performance is reflected
both in an increase in the GPIB bandwidth and a quicker release of the
GPIB talker from the task of transferring data to a slow GPIB device. In
most cases, the GPIB talker is a computer with other tasks to perform. The
faster it transfers data, the sooner it can perform its next task.
Figure 1-1. The GPIB-BUF

Description of the GPIB-BUF Chapter 1
GPIB-BUF User Manual 1-2 © National Instruments Corp.
The GPIB-BUF has two isolated GPIB ports and is placed in-line between a
GPIB system and a single, slower GPIB device (usually a printer or plotter).
The GPIB-BUF automatically buffers all device-dependent data sent to the
slower device. Because the GPIB-BUF can talk or listen on either port at
any time, the GPIB-BUF provides fully transparent bi-directional data
transfers. The target GPIB device appears to be connected directly to the
IEEE 488 bus.
What Your Kit Contains
Your kit should contain the following components:
Component Part Number
One of the following boxes:
• GPIB-BUF (256 KB RAM - 115 VAC) 776226-02
• GPIB-BUF (1 MB RAM - 115 VAC) 776226-03
• GPIB-BUF (256 KB RAM - 230 VAC) 776226-32
• GPIB-BUF (1 MB RAM - 230 VAC) 776226-33
•GPIB-BUF User Manual 320125-01
Optional Equipment
Component Part Number
Rack Mount Kit:
Single (1 unit) 180480-01
Dual (2 units) 180480-02
Double-Shielded GPIB Cables:
GPIB Type X2 Cable – 1 m 763061-01
GPIB Type X2 Cable – 2 m 763061-02
GPIB Type X2 Cable – 4 m 763061-03

Chapter 1 Description of the GPIB-BUF
© National Instruments, Corp. 1-3 GPIB-BUF User Manual
The GPIB-BUF Front Panel
The power switch and six Light Emitting Diodes (LEDs) are mounted on
the GPIB-BUF front panel. Figure 1-2 shows the front panel of the
GPIB-BUF.
GPIB-BUF
IEEE-488 IEEE-488 BUFFER
POWER READY TALK LISTEN EMPTY FULL
NATIONAL
INSTRUMENTS

Figure 1-2. The GPIB-BUF Front Panel
The LEDs show the current status of the GPIB-BUF at all times. The
following table describes each LED.
Table 1-1. LED Descriptions
LED Indication
POWER Indicates that power to the unit has been applied and the
ON/OFF switch is in the ON position.
READY Indicates that the unit is running its power-on self-test
(blinking), has passed its power-on self-test and is ready to
operate (steady on), or has failed the power-on self-test
(steady off).
TALK Indicates that the GPIB-BUF is configured as a GPIB
Talker.
LISTEN Indicates that the GPIB-BUF is configured as a GPIB
Listener.
EMPTY Indicates that the internal data buffer of the GPIB-BUF is
empty.
FULL Indicates that the internal buffer of the GPIB-BUF is full.

Description of the GPIB-BUF Chapter 1
GPIB-BUF User Manual 1-4 © National Instruments Corp.
The GPIB-BUF Rear Panel
Figure 1-3 shows the power cable and the GPIB cables connected to the rear
panel of the GPIB-BUF.
Figure 1-3. The GPIB-BUF Rear Panel
The GPIB Connectors
The GPIB-BUF has two GPIB connectors labeled GPIB IN and GPIB OUT.
Both GPIB connectors are standard 24-pin shielded AMP CHAMP female
connectors with metric screwlock hardware. As you face the rear panel, the
GPIB IN connector is the right-most GPIB connector. The GPIB OUT
connector is located on the left.
Notice that although these GPIB ports are labeled GPIB IN and GPIB OUT,
both are able to transfer data in either direction. The notations GPIB IN and
GPIB OUT are used in order to differentiate the ports since the GPIB IN
port, under normal circumstances, receives data while the GPIB OUT port
normally sends data to the GPIB target device.

Chapter 1 Description of the GPIB-BUF
© National Instruments, Corp. 1-5 GPIB-BUF User Manual
The port labeled GPIB IN is intended to be connected to a GPIB system that
includes one or more GPIB devices which send data to the GPIB target
device. All data received via the GPIB IN port is transferred into the
Random Access Memory (RAM) buffer of the GPIB-BUF using the on-
board Direct Memory Access (DMA) controller. The port labeled GPIB
OUT should be connected to the GPIB target device. This port has GPIB
controller capabilities and addresses the GPIB target device when required.
All data input to the internal GPIB-BUF RAM buffer is output via the GPIB
OUT port. Under normal operating conditions, you should only connect
one device (your GPIB target device) to the GPIB OUT port.
Figure 1-4 shows a diagram of one of the GPIB connectors and the signal
designations. Only one GPIB connector is shown since both connectors
have the same signal and pin descriptions. A * suffix indicates that the
signal is active low.
DIO1*
DIO2*
DIO3*
DIO4*
EOI*
DAV*
NRFD*
NDAC*
IFC*
SRQ*
ATN*
SHIELD
DIO5*
DIO6*
DIO7*
DIO8*
REN*
GND (Twisted Pair with DAV*)
GND (Twisted Pair with NRFD*)
GND (Twisted Pair with NDAC*)
GND (Twisted Pair with IFC*)
GND (Twisted Pair with SRQ*)
GND (Twisted Pair with ATN*)
SIGNAL GROUND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Figure 1-4. The GPIB Connector and Signal Designations

© National Instruments Corp. 2-1 GPIB-BUF User Manual
Chapter 2
Installation and Operation
This chapter describes the procedures for installing and operating the
GPIB-BUF.
Figure 2-1 shows an example of a GPIB-BUF connected to a GPIB system.
This example shows a GPIB-BUF placed in a GPIB system with a GPIB
Talker/Controller, such as an IBM-PC with a National Instruments
GPIB-PCII Controller board installed, and a slow GPIB data acceptor, such
as an HP 7475A Color Plotter. Notice that the GPIB-BUF is placed in-line
between the existing GPIB system and the GPIB target device.
GPIB Cable GPIB-BUF
IEEE 488 IEEE488 BUFFER
POWER READY TALK LISTEN EMPTY FULL
NATIONAL
INSTRUMENTS®
GPIB Cable
Figure 2-1. GPIB-BUF System Setup Example

Installation and Operation Chapter 2
GPIB-BUF User Manual 2-2 © National Instruments Corp.
Installation
Install the GPIB-BUF according to the following procedure.
1. Inspect the GPIB-BUF.
2. Verify the voltage requirement.
3. Configure the operating parameters.
4. Connect the cables.
5. Power on the unit.
These steps are described in more detail in the following subsections.
Step 1. Inspect the GPIB-BUF
Before you install the GPIB-BUF, inspect the shipping container and its
contents for damage. If damage appears to have been caused in shipment,
file a claim with the carrier. Retain the packing material for possible
inspection and/or reshipment.
If the equipment appears to be damaged, do not attempt to operate it.
Contact National Instruments for instructions.
Step 2. Verify the Voltage Requirement
The GPIB-BUF is shipped from the factory with either a 115 V or 230 V
wall-mount power supply.
Verify that the voltage on the power supply matches the voltage that is
supplied in your area.
Warning: Operating the unit at any voltage other than the one specified
could damage the unit.

Chapter 2 Installation and Operation
© National Instruments Corp. 2-3 GPIB-BUF User Manual
Step 3. Configure the Operating Parameters
The GPIB-BUF is shipped from the factory configured to operate at a GPIB
primary address of 5 with the SRQ-on-empty function disabled and device
clear recognition and pass through enabled.
The address specified on the configuration switches should match the GPIB
address of your target device. If the addresses do not match, you must
either change the primary address of your target device or change the
primary address of the GPIB-BUF so that they correspond.
To change the primary address of your target device, refer to the user
manual of the device.
To change the GPIB-BUF primary address, the SRQ-on-empty function, or
the device clear response method, you must open the unit and change the
configuration switches. The following steps describe how to change the
configuration switches.
1. Disconnect power to the GPIB-BUF and disconnect any cables attached
to the rear panel.
2. Remove the two screws on the opposite sides of the rear panel.
Warning: Most of the circuitry in the GPIB-BUF uses advanced
CMOS technology and can be damaged by static electricity.
Avoid touching any of the components and take any
necessary CMOS handling precautions.
3. Grasp the rear panel bezel and pull it straight away from the rest of the
unit. The board should slide out the back of the enclosure.
4. Locate the configuration DIP switch (U38) on the printed circuit board.
5. Set the switches for the desired configuration, as described in the
following section, Set Configuration Switches.
6. Close the unit and reinsert the rear panel screws.

Installation and Operation Chapter 2
GPIB-BUF User Manual 2-4 © National Instruments Corp.
Set Configuration Switches
Use the DIP switch at location U38 on the printed circuit board to configure
the GPIB primary address and operating modes of the GPIB-BUF. The DIP
switch has eight configuration switches. Figure 2-2 shows the factory
default setting.
O
N
O
F
F
Key
= depressed side of switch handle
12345678
Figure 2-2. Factory Default Switch Settings
Table 2-1 and Table 2-2 detail the possible configurations of the eight
switches and what each configuration indicates. For more information on
the different operating modes configured by the switches, refer to
Chapter 3, Technical Information.
Default settings are in shaded rows.
Table 2-1. Configuration Parameters for Switches 1 through 3
Switch Position Indication
1OFF Enables device clear recognition
ON Disables device clear recognition
2OFF Sends DCL to the target and resets the
GPIB-BUF
ON Sends DCL to the target
3OFF Disables SRQ on buffer empty
ON Enables SRQ on buffer empty

Chapter 2 Installation and Operation
© National Instruments Corp. 2-5 GPIB-BUF User Manual
Table 2-2. Configuration Parameters for Switches 4 through 8
Switches
45678 Indication
OFF OFF OFF OFF OFF Sets GPIB primary address 0
OFF OFF OFF OFF ON Sets GPIB primary address 1
OFF OFF OFF ON OFF Sets GPIB primary address 2
OFF OFF OFF ON ON Sets GPIB primary address 3
OFF OFF ON OFF OFF Sets GPIB primary address 4
OFF OFF ON OFF ON Sets GPIB primary address 5
OFF OFF ON ON OFF Sets GPIB primary address 6
OFF OFF ON ON ON Sets GPIB primary address 7
OFF ON OFF OFF OFF Sets GPIB primary address 8
OFF ON OFF OFF ON Sets GPIB primary address 9
OFF ON OFF ON OFF Sets GPIB primary address 10
OFF ON OFF ON ON Sets GPIB primary address 11
OFF ON ON OFF OFF Sets GPIB primary address 12
OFF ON ON OFF ON Sets GPIB primary address 13
OFF ON ON ON OFF Sets GPIB primary address 14
OFF ON ON ON ON Sets GPIB primary address 15
ON OFF OFF OFF OFF Sets GPIB primary address 16
ON OFF OFF OFF ON Sets GPIB primary address 17
ON OFF OFF ON OFF Sets GPIB primary address 18
ON OFF OFF ON ON Sets GPIB primary address 19
(continues)