National Instruments GPIB-232CT User manual

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© Copyright 1988, 1992 National Instruments Corporation.
All Rights Reserved.
GPIB-232CT
User Manual
MicroGPIB®
RS-232 to IEEE-488 Controller
July 1992 Edition
Part Number 320114-01

National Instruments Corporate Headquarters
6504 Bridge Point Parkway
Austin, TX 78730-5039
[phone]
(800) IEEE-488 (toll-free U.S. and Canada)
Technical support fax: [phone]
Branch Offices:
Australia 03 879 9422, Belgium 02 757 00 20, Canada 519 622 9310,
Denmark 45 76 73 22, France 1 48 65 33 70, Germany 089 714 5093,
Italy 02 48301892, Japan 03 3788 1921, Netherlands 01720 45761,
Norway 03 846866, Spain 91 896 0675, Sweden 08 984970,
Switzerland 056 45 58 80, U.K. 0635 523 545

!
!
MicroGPIB Products
National Instruments has developed the MicroGPIB product line to offer a
series of high performance, low cost IEEE-488 support items, packaged in
small all-metal cases, capable of being rack mounted.
Limited Warranty
The GPIB-232CT 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 book may not be copied, photocopied,
reproduced, or translated, in whole or in part, without the prior written
consent of National Instruments Corporation.
Trademarks
MicroGPIB® is a trademark of National Instruments Corporation.
Product names listed are trademarks of their respective manufacturers.
Company names listed are trademarks or trade names of their respective
companies.

!
!
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 A
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 Corp. vii GPIB-232CT User Manual
Preface
The GPIB-232CT User Manual describes the features, functions, and
operation of the Product. The GPIB-232CT 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 rackmounted.
Organization of the GPIB-232CT User Manual
The GPIB-232CT User Manual is organized as follows:
Chapter 1, Description of the GPIB-232CT, contains general information
about the National Instruments GPIB-232CT, the IEEE-488 bus, and the
RS-232 port. This chapter also lists all components and accessories as well
as provides electrical, environmental, and physical specifications.
Chapter 2, The GPIB-232CT Modes of Operation, explains the two modes
of operation of the GPIB-232CT.
Chapter 3, Installation and Configuration in S Mode, contains the S mode
installation and configuration steps.
Chapter 4, Programming in S Mode, explains how to program the
GPIB-232CT when operating in S mode.
Chapter 5, S Mode Functions, gives a detailed description of each S mode
function. The functions are arranged in alphabetical order and each
contains the syntax, purpose, and examples.
Chapter 6, Installation and Configuration in G Mode, contains the G mode
installation and configuration steps.
Chapter 7, Programming in G Mode, explains how to program the
GPIB-232CT when operating in G mode.
Chapter 8, G Mode Functions, gives a detailed description of each G mode
function. The functions are arranged in alphabetical order and each
contains the syntax, purpose, and examples.

Preface
GPIB-232CT User Manual viii © National Instruments Corp.
Appendix A, Multiline Interface Messages, contains an ASCII chart, and a
list of the corresponding GPIB messages.
Appendix B, Status Information, contains explanations of status bits, GPIB
error codes, and serial port error codes.
Appendix C, The Serial Connection, explains the RS-232 serial standard
and contains information for building a serial cable.
Appendix D, Operation of the GPIB, describes the operation of the GPIB.
Appendix E, Common Questions, provides answers to common questions
that frequently arise.
Appendix F, Parallel Polling, explains the use and operation of Parallel
Polls.
Appendix G, Setting Switches, gives additional details about setting
switches on the GPIB-232CT.
Appendix H, Sample Programs, provides some S mode and G mode sample
programs.
Conventions Used in This Manual
Throughout this manual, the following conventions are used to distinguish
elements of text:
italic Italic text denotes emphasis, a cross reference, or
an introduction to a key concept.
monospace Text in this font denotes text or characters that
are to be literally input from the keyboard,
sections of code, programming examples, syntax
examples, and names of variables.
boldface Bold text in this manual denotes a signal name, a
front panel LED indicator, or onscreen module
responses.

Preface
© National Instruments Corp. ix GPIB-232CT User Manual
<> Angle brackets enclose the ASCII character
symbols for certain keystrokes. For example,
<CR> for carriage return and <LF> for linefeed.
Abbreviations
The following abbreviations are units of measure that are used in the text of
this manual.
A ampere
C Celsius
° degree
> greater than
• greater than or equal to
hex hexadecimal
Hz hertz
in. inch
K 1,024
kbytes/sec 1000 bytes per second
< less than
• less than or equal to
m meter
M 1,048,576
Mbytes/sec 1,000,000 bytes per second
mA milliampere
mm millimeter
oz. ounce
% percent
sec second
V volt
VAC volts alternating current
VDC volts direct current

Preface
GPIB-232CT User Manual x © National Instruments Corp.
Customer Communication
We appreciate communicating with the people who use our products. If
you encounter any technical problems, you can use the following toll-free
number between the hours of 8:00 a.m. and 5:30 p.m. (central time) to
reach the National Instruments applications engineering department:
[phone]
(800) IEEE-488 (toll-free U.S. and Canada)
For your documentation comments, we have included a User Comment
Form at the back of the manual. Please mail it to the address printed at the
bottom of the form.

© National Instruments Corp. xi GPIB-232CT User Manual
Contents
Chapter 1
Description of the GPIB-232CT .................................................1-1
Introduction................................................................................1-1
What Your Kit Contains ............................................................1-2
Optional Equipment ...................................................................1-3
GPIB-232CT Specifications.......................................................1-4
The GPIB-232CT Front Panel ...................................................1-5
The GPIB-232CT Rear Panel.....................................................1-7
The RS-232 Port ..........................................................1-8
The GPIB Port .............................................................1-9
Chapter 2
The GPIB-232CT
Modes of Operation.........................................................................2-1
Introduction................................................................................2-1
Choosing Between S Mode or G Mode .....................................2-1
Chapter 3
Installation and
Configuration in S Mode ...............................................................3-1
Installation..................................................................................3-1
Step 1: Inspection ......................................................3-1
Step 2: Verify the Voltage Requirement....................3-2
Step 3: Configure the Operating Parameters .............3-2
Set Configuration Switches ...........................3-3
Default Settings for Configuration Switch ....3-4
Step 4: Connect the Cables ........................................3-5
Step 5: Power on the Unit..........................................3-5
Chapter 4
Programming in S Mode ...............................................................4-1
Programming Messages .............................................................4-1
Programming Message Format....................................4-1
Example of a Programming Message............4-1
Example of a Programming Message
with Data String.............................................4-2
How Messages are Processed ......................................4-2
Function Names .........................................................................4-2
Function Argument Delimiters ..................................................4-3

Contents
GPIB-232CT User Manual xii © National Instruments Corp.
Abbreviations for Arguments ......................................4-3
GPIB Address ..............................................................4-3
Numeric String Argument..........................................................4-4
Status Information......................................................................4-4
Serial Port Error Handling .........................................................4-5
GPIB Read and Write Termination Method (END and EOS) ...4-5
S Mode - Default Settings..........................................................4-6
List of S Mode Functions by Group...........................................4-7
GPIB Functions ...........................................................4-7
Serial Port Functions....................................................4-10
General Use Functions.................................................4-10
Alphabetical List of S Mode Functions .....................................4-11
Chapter 5
S Mode Functions.............................................................................5-1
Points to Remember ...................................................................5-1
cac - Become Active Controller.................................................5-3
caddr - Change the GPIB Address of the GPIB-232CT ............5-4
clr - Clear Specified Device .......................................................5-6
cmd - Send GPIB Commands ....................................................5-8
echo - Echo Characters Received from Serial Port....................5-11
eos - Change/Disable GPIB EOS Termination Mode................5-12
eot - Enable/Disable END Message on GPIB Writes ................5-15
gts - Go from Active Controller to Standby...............................5-17
ibcl - Enter ibcl Operating System .............................................5-19
id - Identify System....................................................................5-21
ist - Set or Clear Individual Status Bit........................................5-22
loc - Go to Local .......................................................................5-23
onl - Place the GPIB-232CT Online/Offline..............................5-25
pct - Pass Control .......................................................................5-26
ppc - Parallel Poll Configure......................................................5-27
ppu - Parallel Poll Unconfigure .................................................5-29
rd - Read Data ............................................................................5-31
rpp - Request (Conduct) a Parallel Poll......................................5-34
rsc - Request System Control.....................................................5-36
rsp - Request (Conduct) a Serial Poll.........................................5-38
rsv - Request Service/Set or Change Serial Poll Status Byte.....5-41
sic - Send Interface Clear ...........................................................5-42
spign - Ignore Serial Port Errors ................................................5-44
sre - Set (or clear) Remote Enable .............................................5-46
stat - Return GPIB-232CT Status...............................................5-47
tmo - Change or Disable Time Limit .........................................5-53
trg - Trigger Selected Device(s).................................................5-55

Contents
© National Instruments Corp. xiii GPIB-232CT User Manual
wait - Wait for Selected Event ...................................................5-57
wrt - Write Data .........................................................................5-60
xon - Change Serial Port XON/XOFF Protocol.........................5-63
Chapter 6
Installation and Configuration in G Mode ...........................6-1
Installation..................................................................................6-1
Step 1: Inspection ......................................................6-1
Step 2: Verify the Voltage Requirement....................6-2
Step 3: Configure the Operating Parameters .............6-2
Set Configuration Switches ...........................6-3
Example Settings for Configuration
Switch............................................................6-6
Step 4: Connect the Cables ........................................6-6
Step 5: Power on the Unit..........................................6-7
Chapter 7
Programming in G Mode ..............................................................7-1
Programming Messages .............................................................7-1
Programming Message Format....................................7-1
Example of a Programming Message............7-1
How Messages are Processed ......................................7-2
Function Names .........................................................................7-2
Function Argument Delimiters ..................................................7-2
Abbreviation for Argument .........................................7-2
Status Information......................................................................7-3
Communicating with the GPIB-232CT and the Serial Device ..7-3
Address of the GPIB-232CT .......................................7-3
Address of the Serial Device .......................................7-3
Addressing Terminology...............................7-3
The GPIB-232CT and Serial Device as Listener .......................7-4
The GPIB-232CT and Serial Device as Talker..........................7-5
GPIB Read and Write Termination (END and EOS).................7-6
Serial Port Transmission ............................................................7-6
G Mode - Default Settings .........................................................7-7
List of G Mode Functions by Group..........................................7-8
GPIB Configuration Functions ....................................7-8
Serial Port Configuration Functions ............................7-9
General Use Functions.................................................7-9
List of G Mode Functions in Alphabetical Order ......................7-10
Operation of the GPIB-232CT with a Serial Device..................7-10
Serial Poll.....................................................................7-11
Service Request ...........................................................7-11

Contents
GPIB-232CT User Manual xiv © National Instruments Corp.
Parallel Poll..................................................................7-12
Trigger .........................................................................7-12
Local ............................................................................7-12
Control .........................................................................7-12
Device Clear ................................................................7-13
Chapter 8
G Mode Functions............................................................................8-1
Points to Remember ...................................................................8-1
echo - Echo Characters Received from Serial Port....................8-3
eos - Change/Disable GPIB EOS Termination Mode................8-5
id - Identify System....................................................................8-7
onl - Place the GPIB-232CT Online/Offline..............................8-8
spign - Ignore Serial Port Errors ................................................8-9
spset - Change Serial Port Parameters .......................................8-10
srqen - Enable/Disable Setting of SRQ......................................8-12
stat - Return GPIB-232CT Status...............................................8-14
xon - Change Serial Port XON/XOFF Protocol.........................8-20
Appendix A
Multiline Interface Messages.......................................................A-1
Multiline Interface Messages .....................................................A-2
Interface Message Reference List ..............................................A-4
Appendix B
Status Information...........................................................................B-1
Status Bits ..................................................................................B-1
GPIB Error Codes ......................................................................B-6
Serial Port Error Codes ..............................................................B-10
Appendix C
The Serial Connection ....................................................................C-1
RS-232C.....................................................................................C-1
Interfacing the GPIB-232CT to a DCE......................................C-3
Interfacing the GPIB-232CT to a DTE ......................................C-5
Buffering and Handshaking .......................................................C-6
Hardware Handshake...................................................C-7
XON/XOFF .................................................................C-8
Appendix D
Operation of the GPIB ...................................................................D-1
Types of Messages .....................................................................D-1
Talkers, Listeners, and Controllers ............................................D-1

Contents
© National Instruments Corp. xv GPIB-232CT User Manual
The Controller-In-Charge and System Controller......................D-3
GPIB Signals and Lines .............................................................D-3
Data Lines....................................................................D-4
Handshake Lines..........................................................D-5
NRFD* (not ready for data) ..........................D-5
NDAC* (not data accepted) ..........................D-5
DAV* (data valid) .........................................D-5
Interface Management Lines .......................................D-5
ATN* (attention) ...........................................D-5
IFC* (interface clear) ....................................D-6
REN* (remote enable)...................................D-6
SRQ* (service request ...................................D-6
EOI* (end or identify) ...................................D-6
Physical and Electrical Characteristics ......................................D-6
Configuration Restrictions .........................................................D-9
Related Document......................................................................D-9
Appendix E
Common Questions..........................................................................E-1
S Mode .......................................................................................E-1
G Mode ......................................................................................E-3
Appendix F
Parallel Polling ..................................................................................F-1
Operation....................................................................................F-1
Configuration .............................................................................F-2
The Parallel Poll.........................................................................F-3
Disabling Parallel Poll Response ...............................................F-3
S Mode Example..........................................................F-3
Appendix G
Setting Switches.................................................................................G-1
Appendix H
Sample Programs .............................................................................H-1
S Mode Sample Programs..........................................................H-1
Using an HP 7475A Plotter with a Terminal .............................H-2
Getting Ready to Program ...........................................H-2
Programming Steps......................................................H-3
Step 1. stat Function .....................................H-3
Step 2. Serial Port Functions ........................H-3
Step 3. GPIB Initialization Functions...........H-4

Contents
GPIB-232CT User Manual xvi © National Instruments Corp.
Step 4. Communicate with
rd and wrt Functions......................................H-4
Using an HP 7475A Plotter with an IBM PC ............................H-5
Getting Ready to Program ...........................................H-5
Programming Steps......................................................H-6
Step 1. stat Function .....................................H-6
Step 2. Serial Port Functions ........................H-6
Step 3. GPIB Initialization Functions...........H-6
Step 4. Communicate with
rd and wrt Functions......................................H-7
Programming a Tektronix 2445 Oscilloscope
from an Apple IIc.......................................................................H-8
Getting Ready to Program ...........................................H-8
Programming Steps......................................................H-9
Step 1. stat Function .....................................H-9
Step 2. Serial Port Functions ........................H-9
Step 3. GPIB Initialization Functions...........H-9
Step 4. Communicate with
rd and wrt Functions......................................H-9
G Mode Sample Programs .........................................................H-10
Using an HP 7475A Plotter with a GPIB Controller .................H-11
Getting Ready to Program ...........................................H-11
Programming Steps......................................................H-12
Step 1. stat Function .....................................H-12
Step 2. GPIB Initialization Functions...........H-12
Step 3. Serial Port
Initialization Functions..................................H-12
Step 4. Communicate with Plotter................H-13
IBM PC (with GPIB-PC) to Serial Printer.................................H-14
Getting Ready to Program ...........................................H-14
Programming Steps......................................................H-15
Step 1. stat Function .....................................H-15
Step 2. GPIB Initialization Functions...........H-15
Step 3. Serial Port
Initialization Functions..................................H-15
Step 4. Communicate with the Printer..........H-15

Contents
© National Instruments Corp. xvii GPIB-232CT User Manual
Figures
Figure 1-1. The GPIB-232CT ............................................................1-1
Figure 1-2. The GPIB-232CT Front Panel.........................................1-5
Figure 1-3. The GPIB-232CT Rear Panel..........................................1-7
Figure 1-4. The RS-232 Connector and Signal Designations ............1-8
Figure 1-5. The GPIB Connector and Signal Designations ...............1-9
Figure 2-1. Personal Computer Controlling a GPIB Plotter ..............2-2
Figure 2-2. A Serial Printer Connected to a GPIB Controller............2-2
Figure 3-1. S Mode Switch Settings ..................................................3-3
Figure 3-2. Factory Default Settings for Switch U22 ........................3-4
Figure 6-1. G Mode Switch Settings..................................................6-3
Figure 6-2. Example Settings for Switch U22 ...................................6-6
Figure C-1. DTE-to-DCE Cable Configuration..................................C-3
Figure C-2. Minimum DTE-to-DCE Cable Configuration.................C-4
Figure C-3. Null Modem Cable Configuration...................................C-5
Figure C-4. Minimum Null Modem Cable Configuration..................C-6
Figure D-1. GPIB Cable Connector....................................................D-4
Figure D-2. Linear Configuration of the GPIB Devices .....................D-7
Figure D-3. Star Configuration of GPIB Devices...............................D-8
Figure G-1. S mode, 7 data bits, 1 stop bit, even parity, 300 baud.....G-1
Figure G-2. S mode, 8 data bits, 1 stop bit, even parity, 19200 baud.G-2
Figure G-3. S mode, 8 data bits, 1 stop bit, no parity, 9600 baud ......G-3
Figure G-4. S mode, 7 data bits, 1 stop bit, even parity, 300 baud.....G-3
Figure G-5. S mode, 8 data bits, 1 stop bit, even parity, 9600 baud...G-4
Figure H-1. S mode, 8 data bits, 1 stop bit, no parity, 19200 baud ....H-2
Figure H-2. S mode, 7 data bits, 1 stop bit, no parity, 9600 baud ......H-5
Figure H-3. S mode, 8 data bits, 1 stop bit, no parity, 9600 baud ......H-8
Figure H-4. G mode, parimary GPIB address 2..................................H-11
Figure H-5. G mode, primary GPIB address 18 .................................H-14

Contents
GPIB-232CT User Manual xviii © National Instruments Corp.
Tables
Table 1-1. Electrical Characteristics .................................................1-4
Table 1-2. Environmental Characteristics.........................................1-4
Table 1-3. Physical Characteristics...................................................1-5
Table 1-4. LED Descriptions............................................................1-6
Table 3-1. Configuration Parameters for Switches 1 through 5 .......3-3
Table 3-2. Configuration Parameters for Switches 6 through 8 .......3-4
Table 4-1. Serial Port Characteristics ...............................................4-6
Table 4-2. GPIB Characteristics .......................................................4-6
Table 4-3. I/O Functions...................................................................4-7
Table 4-4. Bus Management Functions ............................................4-7
Table 4-5. GPIB Initialization Functions..........................................4-8
Table 4-6. Serial Poll Functions .......................................................4-8
Table 4-7. Low-Level Controller Functions .....................................4-9
Table 4-8. Parallel Poll Functions.....................................................4-9
Table 4-9. Serial Port Initialization Functions..................................4-10
Table 4-10. General Use Functions ....................................................4-10
Table 4-11. GPIB-232CT Functions...................................................4-11
Table 5-1. Data Transfer Termination Methods ...............................5-12
Table 5-2. GPIB Status Conditions...................................................5-48
Table 5-3. GPIB Error Conditions....................................................5-49
Table 5-4. Serial Port Error Conditions ............................................5-50
Table 5-5. Wait Mask Values ...........................................................5-58
Table 6-1. Primary Address Configurations .....................................6-4
Table 7-1. GPIB Characteristics .......................................................7-7
Table 7-2. Serial Port Characteristics ...............................................7-7
Table 7-3. GPIB Configuration Functions........................................7-8
Table 7-4. Serial Port Configuration Functions................................7-9
Table 7-5. General Use Functions ....................................................7-9
Table 7-6. GPIB-232CT Functions...................................................7-10
Table 7-7. Serial Poll Response Byte ...............................................7-11
Table 8-1. Data Transfer Termination Methods ...............................8-5
Table 8-2. SRQ Mask Bits................................................................8-12
Table 8-3. GPIB-232CT Status Conditions ......................................8-15
Table 8-4. GPIB Error Conditions....................................................8-16
Table 8-5. Serial Error Conditions....................................................8-17

Contents
© National Instruments Corp. xix GPIB-232CT User Manual
Table C-1. RS-232 Serial Port Pinouts..............................................C-2

© National Instruments Corp. 1-1 GPIB-232CT User Manual
Chapter 1
Description of the GPIB-232CT
Introduction
The GPIB-232CT, shown in Figure 1-1, is a high-performance serial-to-
GPIB interface. It provides a computer with an RS-232 port, a means of
controlling, talking, and listening on the GPIB. The GPIB-232CT is also
capable of interfacing RS-232 instruments and peripherals to the GPIB.
The GPIB-232CT has all the software and logic required to implement the
physical and electrical specifications of the IEEE-488 and the RS-232
standards. It is capable of both interpreting and executing high-level
commands that you send to it over the serial port, and performing GPIB-to-
RS-232 protocol conversion.
Figure 1-1. The GPIB-232CT