National Instruments GPIB-LPT User manual

© Copyright 1989, 1990 National Instruments Corporation.
All Rights Reserved.
GPIB-LPT
User Manual
October 1989 Edition
Part Number 320161-01

National Instruments Corporation
6504 Bridge Point Parkway
Austin, TX 78730-5039
[phone]
(800) IEEE-488
Fax: [phone]

Limited Warranty
The GPIB-LPT hardware is warranted against defects in materials and workmanship for a period
of two years from date of shipment from National Instruments or its authorized dealer. The
GPIB-LPT Diagnostic Package software media is furnished warranted to be free from defects in
materials and workmanship under normal use for a period of 90 days from date of shipment from
NI or its authorized dealer. National Instruments will repair or replace equipment which proves to
be defective during the warranty period. This warranty includes parts and labor. A Return
Material Authorization (RMA) number must be obtained from National Instruments before any
equipment is returned for repair. Faults caused by misuse are not covered under the warranty.
During the warranty period, the owner may return failed parts to National Instruments for repair.
National Instruments will pay the shipping costs of returning the part to the owner. All items
returned to National Instruments for repair must be clearly marked on the outside of the package
with an RMA number. Defects caused by misuse, abuse, or shipment are not covered.
The GPIB-LPT Diagnostic Package software program is provided "as is" without warranty of any
kind, either expressed or implied. No other warranty is expressed or implied. NI shall not be
liable or responsible for any kind of damages, including special, indirect, or consequential
damages, arising or resulting from its products, the use of its products, or the modification to its
products.
Important Notice
The material in this manual is subject to change without notice. National Instruments assumes no
responsibility for errors which may appear in this manual. National Instruments makes no
commitment to update, nor to keep current, the information contained in this document.
Copyright
Under the copyright laws, this manual may not be copied, photocopied, reproduced, translated, in
whole or in part, without the prior written consent of National Instruments Corporation.
Trademarks
IBM PC and AT are registered trademarks and PC XT is a trademark of International Business
Machines Corporation.
TI Professional Computer is a trademark of Texas Instruments.

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 (1) the limits for a Class B
computing device, in accordance with the specifications in Subpart J of Part 15 of U.S. Federal
Communications Commission (FCC) Rules, and (2) the limits for radio noise emissions from
digital apparatus set out in the Radio Interference Regulations of the Canadian Department of
Communication (DOC). These regulations are designed to provide reasonable protection against
interference from the equipment to radio and television reception in commercial areas.
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 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.
• Relocate the equipment with respect to the receiver.
• Reorient 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.
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 Corporation v GPIB-LPT User Manual
Preface
This manual is divided into the following sections.
Section One, Introduction, contains a brief description of the GPIB-LPT including its features,
components, and accessories.
Section Two, Configuration and Installation, describes how to configure and install the GPIB-
LPT into your system.
Section Three, Function Description, shows a block diagram of the GPIB-LPT and describes the
functional components of the GPIB-LPT.
Section Four, Running Diagnostic Tests, describes how to run the diagnostic tests that are shipped
with the GPIB-LPT.
Section Five, Programming the GPIB-LPT, contains specific information about the GPIB-LPT
registers along with software examples.
Appendix A, Operation of the GPIB, describes GPIB terminology and protocol for users
unfamiliar with the GPIB.
Appendix B, Multiline Interface Messages, contains an ASCII chart and a list of the corresponding
GPIB messages.
Abbreviations Used in This Manual
The following abbreviations are used in the text of this manual.
A ampere
hex hexadecimal
kbytes 1,000 bytes
m meter
Mbytes 1,000,000 bytes
µsec microsecond
sec second
V volt
VDC Volts direct current

Preface
GPIB-LPT User Manual vi © National Instruments Corporation
Related Documents
The following documents are references that cover in greater detail specific topics introduced in
this manual:
•ANSI/IEEE Standard 488-1978, IEEE Standard Digital Interface for Programmable
Instrumentation
•IBM Options Adapters Manual

© National Instruments Corporation vii GPIB-LPT User Manual
Contents
Section One
Introduction .................................................................................................................1-1
Features............................................................................................................................1-1
What Your Kit Should Contain ...................................................................................... 1-3
Optional Equipment ........................................................................................................1-3
Section Two
Configuration and Installation
..................................................................2-1
Configuration .................................................................................................................. 2-2
Switch and Jumper Settings ................................................................................2-3
Base I/O Address and Interrupt Selection ...........................................................2-3
Listen Address and Control Function Selection ..................................................2-5
Installation........................................................................................................................2-8
Section Three
Function Description
...........................................................................................3-1
Address Decoding ..........................................................................................................3-2
Configuration Jumpers ...................................................................................................3-2
Data and Control Latches ................................................................................................ 3-2
Data Transceivers ............................................................................................................3-2
Data Wrap, Control Wrap and Status Buffers ................................................................3-2
External Device Listen Address Switch .......................................................................... 3-2
GPIB Handshaking ......................................................................................................... 3-3
GPIB Addressing ........................................................................................................... 3-3
Section Four
Running Diagnostic Tests
................................................................................4-1
The GPIB-LPT Test Commands .................................................................................... 4-1
-1 printer test .......................................................................................................4-1
-2 plotter test .......................................................................................................4-2
-c change LPT configuration ............................................................................... 4-3
-q quit ..................................................................................................................4-3
Section Five
Programming the GPIB-LPT
.......................................................................5-1
The GPIB-LPT Registers ................................................................................................ 5-1
Data Register (DATA) ........................................................................................ 5-2
Status Register (STAT) .......................................................................................5-3
Control Register (CTRL) .................................................................................... 5-5
Programming Considerations .........................................................................................5-6
Using the GPIB-LPT with the DOS Operating System .....................................5-6
Using the GPIB-LPT with C and BASIC ...........................................................5-6
Acessing the Parallel Port in C ................................................................5-7
Acessing the Parallel Port in BASIC ...................................................... 5-7

Contents
GPIB-LPT User Manual viii © National Instruments Corporation
Writing a GPIB-LPT Driver ...............................................................................5-7
Setup and Initialization ............................................................................5-8
Interrupt Handler Routine .......................................................................5-8
PRINT Routine ........................................................................... 5-8
Timing Constraints.................................................................................. 5-9
Appendix A
Operation of the GPIB
.......................................................................................A-1
History of the GPIB .......................................................................................................A-1
Types of Messages ........................................................................................................A-1
Talkers, Listeners, and Controllers .................................................................................A-1
System Controller and Active Controller .......................................................................A-2
GPIB Signals .................................................................................................................A-2
Data Lines ......................................................................................................................A-3
Handshake Lines ............................................................................................................A-3
NRFD (not ready for data) .................................................................................A-3
NDAC (not data accepted) .................................................................................A-3
DAV (data valid) ...............................................................................................A-3
Interface Management Lines ..........................................................................................A-4
ATN (attention) ..................................................................................................A-4
IFC (interface clear) ...........................................................................................A-4
REN (remote enable) .........................................................................................A-4
SRQ (service request) ........................................................................................A-4
EOI (end or identify) .........................................................................................A-4
Physical and Electrical Characteristics ...........................................................................A-5
Configuration Restrictions .............................................................................................A-7
Appendix B
Multiline Interface Messages
........................................................................B-1
Appendix C
Specifications
...............................................................................................................C-1

Contents
© National Instruments Corporation ix GPIB-LPT User Manual
Figures
Figure 1-1. GPIB-LPT Board ..................................................................................................1-2
Figure 2-1. GPIB-LPT Parts Locator Diagram .......................................................................2-1
Figure 2-2. Possible Settings for GPIB-LPT Jumpers ............................................................2-4
Figure 2-3. Switch Setting for REN OFF, IFC ON, SRQ ON , and Address 5 .....................2-5
Figure 2-4. Setting for Address 6 hex .....................................................................................2-6
Figure 2-5. Switch Setting for REN ON, IFC ON, and SRQ OFF ........................................2-7
Figure 3-1. GPIB-LPT Block Diagram ...................................................................................3-1
Figure 4-1. Plotter Output ........................................................................................................4-2
Figure A-1. GPIB Cable Connector .........................................................................................A-3
Figure A-2. Linear Configuration of GPIB Devices .................................................................A-5
Figure A-3. Star Configuration of GPIB Devices ....................................................................A-6
Tables
Table 2-1. IBM PC Parallel Port Adapters ..............................................................................2-2
Table 2-2. Factory Default Settings and Optional Configurations ........................................... 2-3

© National Instruments Corporation 1-1 GPIB-LPT User Manual
Section One
Introduction
The National Instruments GPIB-LPT is a high-performance talk-only interface that converts data
sent to a standard parallel port into an IEEE-488 General Purpose Interface Bus (GPIB) format for
use with IEEE-488 printers and plotters. The GPIB-LPT looks like a standard parallel port for the
IBM PC operating system and software. It can be used to communicate with GPIB printers and
plotters with PC application programs, such as AutoCAD, that use parallel ports for printer and
plotter output.
Features
The GPIB-LPT has the following hardware features:
• emulates the standard PC parallel printer interface so that no additional software is needed
• can be configured as either LPT1 (PRN), LPT2, or LPT3
• compatible with any software using the parallel ports on the IBM PC compatibles
• small dimensions so that it fits into any slot of a personal computer
• transparent addressing of unaddressed listeners
• interrupt synchronization circuitry which holds off interrupts until the GPIB handshake is
complete
• choice of REN mode which operates an instrument in the remote mode
• choice of SRQ enable which monitors of asynchronous service requests
• choice of IFC mode which sends an interface clear when the computer is powered on