National Instruments GPIB-MAC User Manual

National

Instruments

Model GPIB-MAC User Manual

Part Number 320064-01

November 1985 Edition

National Instruments

12109 Technology Boulevard

Austin, Texas 78727

[phone]

©

Copyright 1985 by National Instruments

All Rights Reserved

LIMITED WARRANTY

The GPIB-MAC is warranted against defects in materials and work­manship for a period of one year from date of shipment.

National
Instruments will repair or replace equipment which proves to be
defective during the warranty period. This warranty includes parts
and labor. A Returned Material Authorization (RMA) number must
be obtained from the factory before any equipment is returned for
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 a RMA.

No other warranty is
expressed or implied National Instruments shall not be liable for
consequential damages. Contact National Instruments for more

information.

IMPORTANT NOTE

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.

Trademarks

GPIB-MAC is a trademark of National Instruments.
Apple and Macintosh are trademarks of Apple Computer, Inc.

Microsoft is a registered trademark of Microsoft Corporation.

FCC RADIO FREQUENCY INTERFERENCE

COMPLIANCE

This equipment generates, uses, and can radiate radio frequency
energy and if not installed and used in accordance with the
instruction manual, may cause interference to radio communica­tions. It has been tested using a shielded serial I/O cable and
standard GPIB cable and found to comply within the limits for a
Class A computing device pursuant to Subpart J of Part 15 of FCC
Rules, which are designed to provide reasonable protection against
such interference when operated in a commercial environment
Operation of this equipment in a residential area is likely to cause
interference, in which case the user at his own expense will be
required to take whatever measures may be necessary will be
required to take whatever measures may be necessary to correct the
interference.

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.

Reposition the equipment or receiver.
Reposition the receiver’s antenna.
Unplug any unused I/O cables. Unterminated I/O cables are a

potential source of interference.

Remove any unused circuit boards. Unterminated circuit boards
are also a potential source of interference.

*

Be sure the computing device is plugged into a grounded outlet
and that the grounding has not been defeated with a cheater plug.

*

Replace the GPIB cable with Hewlett-Packard Model 10833
cable.

If none of these measures resolves your interference problems,
contact the manufacturer or write to the U.S. Government Printing
Office, Washington, D.C. 20402, for the booklet, “How to Identify

and Resolve Radio-TV Interference Problems, “Stock Number 004­000-000345-4.

©

November 1985

National Instruments

Preface

Welcome to the family of National Instruments GPIB products and
to the Model GPIB-MAC.

The Model GPIB-MAC allows the GPIB to be controlled from a
Macintosh personal computer.

About the Manual

The manual is designed for users who have some familiarity with
the Macintosh personal computer, the GPIB, and test and meas­urement equipment.

For users with less experience, we have included appendixes that
describe the operation of the GPIB.

For more specific details on the operation of the GPIB, refer to the
IEEE Std. 488-1978, “IEEE Standard Digital Interface for Program­mable Instrumentation.”

Whatever your level of experience, if you encounter problems,
National Instruments has a staff of applications engineers ready to
help you with your particular problem. Just call

800/53
800/531-5066 (outside Texas)

800/IEEE-488
between the hours of 8:00 a.m and 5:00 p.m, Central Time.
Now, look over the next few pages at how the manual is organized

and then at the Table of Contents so that you will be familiar with
the complete contents for future reference.

vii

PREFACE

l-GPIB

(inside Texas)

November 1985

Organization of the Manual

©

National Instruments

Section

One -

Section Two
Section Three
Section Four

Appendix A
Appendix B
Appendix C

Appendix D
Appendix F
Appendix F

gives brief introductions to the GPIB-MAC and the
IEEE-488.

contains the installation and configuration steps.

­explains how to program the GPIB-MAC.

­gives a detailed description of each function. The

­function descriptions are arranged in alphabetical
order and each contains the syntax and purpose of
the functions, and examples.

-

contains a table of multiline interface messages.

-

lists status information.

-

shows how to change the operating voltage from

115 to 230.

-

describes the operation of the GPIB.

-

gives answers to common questions.

-

explains the use and operation of Parallel Polls.

Appendix G

Appendix H

Appendix1

. . .

Vlll

PREFACE

-

gives additional detail on setting switches on the
GPIB-MAC.

-

contains a sample program of general programming
steps.

-

contains a sample program to control the serial port
of the Macintosh from a C program.

November 1985

©

National Instruments

TABLE OF

1 SECTION ONE
1
1
1 Description of the Model GPIB-MAC

2

2 Physical Specifications
3
3
4
6
6

7

::

7

!

9

10
11
12
14
15

Introduction to the GPIB-MAC
Introduction to the IEEE-488 (GPIB)

Environmental Specifications

Quick Reference Chart
The Model GPIB-MAC Front Panel
The Model GPIB-MAC Back Panel
Mechanical Specifications

Electrical Specifications

SECTION TWO

Inspection
Installation

Voltage Requirements

Configure the GPIB-MAC Rear Panel Switches

Switches 1 and 2 - Factory Use Only
Switch 3 - Word Length
Switch 4 - Stop Bits
Switches 5 and 6 - Parity Type

Switches
Connect Cables
Turn Power Switch to On

-

Introduction

-

Installation and Configuration

7,8,

and 9 - Baud Rate

CONTENTS

17 SECTION THREE

17

17
18
18
19
19

19

;:
;:

22

ix

Programming Messages

ProgrammingMessage Format

How Messages are Processed
Function Names
Function Argument Delimiters

Abbreviations for Arguments

GPIB Address
Numeric String Argument

Status Information

Serial Port Error Handling
GPIB Read and Write Termination Method
Default Settings

TABLE OF

CONTENTS

-

Programming the GPIB-MAC

November 1985

List of Functions by Group

;:

GPIB Functions

Serial Port Functions

;z

25

General Use Functions

List of Functions in Alphabetical Order

27 SECTION FOUR- Functions

Points to Remember

cat -

Become Active Controller

caddr -

Change the

GPIB

Address of the GPIB-MAC
clr - Clear Specified Device *
cmd - Send GPIB Commands
echo - Echo Characters Received from Serial Port
eos - Change/Disable GPIB EOS Termination Mode
eot - Enable/Disable END Message on GPIB Writes

gts - Go from Active Controller to Standby

id.MAC -

Identify System
ist - Set or Clear Individual Status Bit

lot-GotoLocal*
on1 -

Place the GPlB-MAC Online/Offline

pet - Pass Control

ppc - Parallel Poll Configure
ppu - Parallel Poll Unconfigure
rd - Read Data *
rpp - Request (Conduct) a Parallel Poll

rsc - Request or Release System Control
rsp - Request (Conduct) a Serial Poll
rsv - Request Service/Set or Change Serial Poll Status Byte

sic - Send Interface Clear
spign - Ignore Serial Port Errors
sre - Set or Clear Remote Enable
stat - Return GPIB-MAC Status
tmo - Change or Disable Time Limit

trg -

Trigger Selected Device(s) *
wait - Wait for Selected Event
wrt-WriteData*
xon

-

Change Serial Port XON/XOFF Protocol

0

National Instruments

* frequently used function

TABLE OF CONTENTS

x

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93 APPENDIX A - Multiline Interface Messages

National Instruments

97 APPENDIX B

97

100
103

105 APPENDIX C
107 APPENDIX D - Operation of the GPIB

107

107
108
109
110
110
111
111
114

115 APPENDIX E - Common Questions

117 APPENDIX F - Parallel Polling

:::

119

119
119

Status Bits
GPIB Error Codes
Serial Port Error Codes

Types of Messages
Talkers, Listeners, and Controllers
System Controller and Active Controller
GPIB Signals

Data Lines

Handshake Lines

Interface Management Lines
Physical and Electrical Characteristics
Configuration Restrictions

Configuration

Operation

The

Parallel Poll

Disabling Parallel Poll Response

Example

-

Status Information

-

Changing from 115 VAC to 230 VAC

121 APPENDIX G - Setting Switches
123 APPENDIX H - Sample Program

123
123

123

xi

General Steps

Using an HP 7475A Plotter with a Macintosh

Getting Ready to Program

TABLE

OF

CONTENTS

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124
124
125
125
125

127

Programming Steps

Step

1

-

stat Function
Step 2 - Serial Port Functions
Step 3 - GPIB Initialization Functions
Step 4 - Communicate with rd and wrt

APPENDIX I - Serial Port Sample Program

Functions

xii

TABLE

OF CONTENTS

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LIST OF FIGURES

SECTION ONE

-

Introduction
2 Model GPIB-MAC
3

Front Panel of the GPIB-MAC

5

Back Panel of the Model GPIB-MAC

SECTION TWO

8

GPIB-MAC DIP Switch

8

Factory Use Only

9

7-bit Word Length

9

8-bit Word Length
10 1 Stop Bit
10 2 Stop Bits
11

Configuration for Parity Types
12 Baud Rate Settings
14

GPIB-MAC with Serial Cable, Power Cable, and GPIB Cable

-

Installation and Configuration

APPENDIX C - Changing from 115 Volts AC to 230

Volts AC

105 GPIB-MAC with Cover Removed

APPENDIX D - Operation of the GPIB

109 GPIB Cable Connector
112 Linear Configuration of GPIB Devices
113 Star Configuration of GPIB Devices

xiii

TABLE OF CONTENTS

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LIST OF TABLES

SECTION ONE

Front Panel LEDs

4

SECTION THREE
22 Serial Port Characteristics
22 GPIB Characteristics
23 I/O Functions
23 Bus Management Functions
23 GPIB Initialization Functions
24 Serial Poll Functions

24 Low-level Controller Functions
24 Parallel Poll Functions

Serial Port Initialization Functions

25
25 General Use Functions
25 GPIB-MAC Functions

-

Introduction

-

Programming the GPIB-MAC

SECTION FOUR - Functions

Data Transfer Termination Methods

39

76 GPIB Status Conditions
77 GPIB Error Conditions

Serial Port Error Conditions

78
86 Wait Mask Values

xiv

TABLE

OF CONTENTS

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November 1985

-

Section One

This section provides brief introductions to the GPIB-MAC and the
IEEE-488. It also describes the physical, electrical, and
environmental characteristics of the GPIB-MAC.

Introduction

National Instruments

Introduction to the GPIB-MAC

The GPIB-MAC is a high performance GPIB-to-Macintosh
interface. The GPIB-MAC together with a Macintosh personal
computer provide a means of Controlling, Talking, and Listening on
the GPIB.

The GPIB-MAC has all the software and logic required to
implement the physical and electrical specifications of the IEEE-488.
It is capable of interpreting and executing high level commands that
you send to it over the Macintosh serial port.

Introduction to the IEEE-488 (GPIB)

The IEEE-488, also known as the General Purpose Interface Bus or
GPIB, is a high speed parallel bus structure originally designed by
Hewlett-Packard. It is generally used to connect and control
programmable instruments, but has gained popularity in other
applications, such as intercomputer communication and peripheral
control.

The specifications of the GPIB are too lengthy and comprehensive
to be explained in this manual. However, Appendix D, ‘Operation
of the GPIB,” contains a summary of pertinent IEEE-488

information you might find useful.

Description of the Model GPIB-MAC

Included here are the GPIB-MAC environmental, physical, and
electrical specifications.

1

SECTION ONE - INTRODUCTION

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National Instruments

Environmental Specifications

The GPIB-MAC is designed to operate in temperatures ranging from

10 to 40 degrees Celsius, and in humidity ranging from 10% to 95%

non-condensing.
The GPIB-MAC can be stored in temperatures ranging from 0 to 70

degrees Celsius.

Physical Specifications

The GPIB-MAC, shown in the following figure, is housed in a
structural foam injection molded case. The unit can be rack mounted
or placed on a table.

Model GPIB-MAC

2

SECTION ONE - INTRODUCTION

November 1985

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National Instruments

Ouick Reference Chart.

On the back panel of the GPIB-MAC is a reference chart that
contains the information you need to configure the rear panel
switches of the GPIB-MAC. More detailed configuration
information is included in Section Two.

The Model GPIB-MAC Front Panel

The front panel of the GPIB-MAC is shown in the following figure.
The six light emitting diodes (LEDs) show the current status of the
GPIB-MAC.

3

SECTION

NATIONAL

INSTRUMENTS

IEEE-488 (MAC

[‘-p*ll’;“~][^;“l

Front Panel of the GPIB-MAC

ONE -

INTRODUCTION

GPIB-MAC

0

November 1985

The following table shows what each LED indicates when lit.

National Instruments

LED

POWER
READY

TALK

LISTEN

ATN

SRQ

PurDose

indicates power is on.
indicates that the power-on self-test has passed

successfully and unit is ready to operate.
indicates that the GPIB-MAC is currently

addressed to Talk on the GPIB.
indicates that the GPIB-MAC is currently

addressed to Listen on the GPIB.
indicates that the GPIB signal line ATN* is

asserted (low).
indicates that the GPIB signal line SRQ* is

asserted (low).

The Model GPIB-MAC Back Panel.

The

back panel of the GPIB-MAC is shown in the following figure.
The power connector, 9-position configuration switch, g-pin D-
subminiature connector, and GPIB (IEEE-488) port are shown.

4

SEaION

ONE - INTRODUCTION

November 1985

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National Instruments

g-pin

D-subminiature

Connector

Back Panel of the Model GPIB-MAC

5

SECTION ONE - INTRODUCTION

Power

Connector

9-position

Configuration

Switch

GPIB

(IEEE-488)

Port

November 1985

0

National Instruments

Mechanical

Width:

Height:

Depth:

Weight:

&ecificationS

216.9 mm (8.5 inches)

88.4 mm (3.5 inches)

330.2 mm (13.0 inches)

5.25 pounds

Electrical Specifications

The GPIB-MAC is designed to operate under the following electrical
specifications.

Power:

115

volts AC or 230 volts AC; 50/60 Hz;
20 VA

Typical Current:

Fuse Type:

.09

amps AC

115

230

volts AC use

l/4

amp Fast

volts AC use l/8 amp Fast

6

SECTION ONE - INTRODUCTION

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November 1985

Section Two

-

Installation and

National Instruments

Configuration

Use this section to install and configure the GPIB-MAC. Then,
read Sections Three and Four to learn about how to program the

GPIB-MAC.

Inspection

Before you install the GPIB-MAC, 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
packaging material for possible inspection or for reshipment.

If the equipment appears to be damaged, do not attempt to operate
it. Contact National Instruments for instructions.

Installation

There are four basic steps to installing the GPIB-MAC.

1. Verify voltage requirements

2. Configure GPIB-MAC rear panel switches

3. Connect cables

4. Turn power switch to On

Voltage Requirements
The

GPIB-MAC is shipped with the internal voltage selector switch

configured to operate on a standard 115 VAC power line.
If your setup requires 230 VAC, refer to Appendix C to learn how

to open the box to change the voltage selector switch.

7

SECTION TWO: INSTALLATION AND CONFIGURATION

November 1985

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National Instruments

Configure the GPIB-MAC Rear Panel Switches

Configure the GPIB-MAC by setting the switches of the g-pin, rear
panel DIP switch. The following figure shows the switches
labeled for factory use only, 7- or

g-bit

word length, one or two

stop bits, odd/even or no parity, and baud rate.

D=OFF
l=ON

011

4800

100

9600

101

19.2K

110

38.4K

111

57.6K

GPIB-MAC DIP Switch

Switches 1 and 2 - Factorv Use

Only

Switch 1 and 2 are for factory use only and should always be

positioned in the off position as shown below.

Factory Use Only

8

SECTION TWO: INSTALLATION AND CONFIGURATION

November 1985

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National Instruments

Switch 3

Configure the
setting switch 3. The off position indicates 7 bits, the on position
indicates 8.

-

Word

Length

GPIB-MAC

for a serial word length of 7 or 8 bits by

7-bit

Word Length

g-bit

Word Length

9

SECTION TWO: INSTALLATION AND CONFIGURATION

0

National InstrumentsNovember 1985

Switch 4

- StoD

Bits

Configure the GPIB-MAC for a stop bit length of 1 or 2 bits by
setting switch 4. The off position indicates 1 bit, the on position

indic&s

2.

1 Stop Bit

2 Stop Bits

10

SECTION TWO: INSTALLATION AND CONFIGURATION

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National Instruments

Switches 5 and 6 - Paritv

TVD~

The GPIB-MAC can transmit and receive serial data using odd
parity, even parity, or no parity. Configure the GPIB-MAC for
the correct parity according to the following figure. Note that
switch 5 indicates parity off. Switch 6 indicates parity odd or
even. If switch 5 is set to off, switch 6 is ignored.

Switch Settines

_

1 2 3 415

6i7

8 9

Parity

Odd

Even

Type

Parity

Parity

11

SECTION

Pa&y Inhibit

Parity

b_______.

Two:

INSTALLATION AND CONFIGURATION

Inhibit

0

November 1985

.

witches 7. 8. and 9 - Baud Rate

Configure the GPIB-MAC for the appropriate baud rate by setting
switches

7,8,

and 9 according to the following figures.

National Instruments

Switch Settings

~1

1200

Baud Rate

300

2400

4800

12

SECTION TWO: INSTALLATION AND CONFIGURATION

November 1985

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National Instruments

Baud

9600

19.2K

38.4K

57.6K

If you need more information on how the switches of the GPIB-

MAC

should be set, refer to Appendix G.

13

SECTION TWO: INSTALLATION AND CONFIGURATION

November 1985

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National Instruments

Connect Cables

You must connect three cables to operate the GPIB-MAC: the serial
cable, the power cable, and the GPIB cable. The three cables all
connect to the GPIB-MAC via the rear panel, as shown in the
following figure.

GPIB-MAC with Serial Cable, Power Cable, and GPIB

Cable

The power cord receptacle is located at the top left of the rear panel.

If 115 VAC is required, use the standard power cable supplied with
the unit. If 230 VAC is required, use a cable that is compatible with
both the GPIB-MAC power receptacle and the 230 VAC plug
configuration.

The GPIB cable should be connected to the 24-pin GPIB connector
on the lower right of the rear panel. The connectors can be piggy­backed to add more GPIB devices to the bus. Connect the serial
cable to the
GPIB-MAC. Connect the other end of the cable to your Macintosh
modem port.

14

SECTION TWO: INSTALLATION AND CONFIGURATION

9-p&

D-subminiature connector on the back of the

November 1985

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National Instruments

Turn Power Switch to On

The power switch is located at the left of the power cord receptacle.
Turn the switch to On. There will be a slight delay while the unit
performs a self-test of all the internal circuitry. The test does not
affect devices connected to the GPIB-MAC. When the test
successfully completes, the BEADY LED comes on. If it does not,
verify your switch settings and the power connections. If the
BEADY LED still fails to come on, contact National Instruments.

Note - The rear panel switches are read by the fiiware only when

the unit is powered on. After changing switch settings, turn the

power switch off and back on for the change to take effect. Also,

the GPIB address of the GPIB-MAC at power on is 0 with
secondary addressing disabled. You can change these values after
power-on using a programming message.

15

SECTION TWO: INSTALLATION AND CONFIGURATION

November 1985

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National Instruments

Section Three - Programming the GPIB-MAC

This section shows how to program the GPIB-MAC by using
programming messages and data strings. It describes programming
messages, their format, and how they areprocessed, along with the
functions and function arguments that make up the programming
messages.

Programming Messages

You program the GPIB-MAC by sending it programming messages

(which are ASCII strings) and data strings by way of its serial port.

Programming Message Format

A

arguments (optional), followed by a carriage return (<CR>), a

linefeed (<LF>),

(<CR><LF>).

You may enter programming messages in any combination of
uppercase and lowercase letters.

Example of 3 Proaramming Message

The following line of BASIC code:

contains the function name
programming message tells the GPIB-MAC to clear the devices at
GPIB addresses 3 and 4. PRINT #l is the BASIC command to
send characters to the serial port after the serial port has been opened
with the “OPEN COM...” statement. In this example, BASIC
automatically sends a

17

amming message consists of a function name, one or more

progr

or a carriage return followed by a

PRINT

<CR>,

SECTION THREE - PROGRAMMING THE GPIB-MAC

#l,“clr 34”

clr

and the arguments 3 and 4. This

so it is not necessary to include it here.

linefeed

November 1985

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National Instruments

The cmd

string which may contain 7- or

Example ef 1~

The following lines of BASIC code:

contain the function name

“IN;CI;“.

write to the device at primary address 2.

“IN;CI;” is the data string which contains the data

on the GPIB. In this case, a
following each print string, so, again, it is not necessary to include it
here.

and

wrt

programming messages are followed by a data

ProFamming

PRINT # 1,
PRINT

This programmin

g-bit

data

Message with Data String

“wrt 2”

#l, ‘TN;CI;”

wrt, the

g

<CR>

argument 2, and the data string

message is telling the GPIB-MAC to

wrt

will send out

is automatically sent by BASIC

How Messages are Processed

g

The GPIB-MAC processes a programmin
line basis. The GPIB-MAC buffers the entire message, interprets
the function name and arguments, then executes the message.

message on a line-by-

The data portions of the
on a line-by-line basis. The data immediately following a

cmd are

sent directly to the GPIB.

wrt

and

cmd

functions are not processed

wrt

and a

Function Names

The function names have been selected to indicate each function’s
purpose, thereby making your programs easy to understand.
However, if you wish to reduce some overhead in your program
and do not mind giving up these advantages, you may use only as
much of the function name as is necessary to distinguish it from
other functions. This abbreviated form of the function name is
shown in
of the function descriptions.

18

boldface in the

SECTION THREE - PROGRAMMING THE GPIB-MAC

function tables and in the syntax portions

November 1985

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National Instruments

For example, the

wait

function may be called using either of the

next two statements:

PRINT
PRINT

#l,

#l,

“wait

“wa

\x5000”

\x5000”

Function Argument Delimiters

When you type in a function, separate the
function name with at least one space. Separate each additional
argument with at least one space or a comma.

In the syntax portions of the function descriptions in Section Four
the square brackets

(n)

are optional. If you want to include optional
information, you do not need to type the brackets, only the
information inside the brackets.

Abbreviations for Arguments

The function descriptions in Section Four use abbreviations for

some arguments. They are as follows:

addr a GPIB address

alist one or more addrs
boo1

a boolean value: 1 = true, on, or enable

0 = false, off, or disable

fmt

argument from the

GPIB Address

Each device on the GPIB has a GPIB address. The GPIB-MAC’s
address is 0 at power on and may be changed using the

caddr

function. Refer to the manuals of your GPIB devices to learn their

addresses. You will need to know these when you begin to

program the GPIB-MAC.

Only the lower five bits of each GPIB address are significant. These
bits may be in the range from 0 through 30 for both the primary and
the secondary address. For example, the binary value 01100010
(decimal 98) is interpreted as decimal 2.

19

SECTION

THREFi -

PROGRAMMING THE GPIB-MAC

November 1985

The following examples all specify a primary address of 0 and a

secondary address of 2. A plus sign
address from the secondary address. The listen address is 32
(primary address plus

plus

64),

and the secondary address is 2 or 98, which are

equivalent. The next paragraph explains the \x notation.

0+2

32),

the talk address is 64 (primary address

or

0+98

or

32+98

0

National Instruments

(+)

separates the primary

or

O+\x62

Numeric String Argument

Another type of argument is a numeric string.
represents an integer, which you may express using decimal, octal,
or hexadecimal digits. To specify an octal integer, precede it with a
backslash
backslash x ox) or backslash X

Each of the following numeric strings represents the decimal integer
value 112:

The GPIB address argument described previously under “GPIB
Address” consisted of one or two numeric strings.

0).

To specify a hexadecimal integer, precede it with a

OX).

112

\160
\x70

A numeric string

Status Information

The function descriptions in Section Four explain that the GPIB-

MAC “records” specific status and error information. This means

that it stores that information in its memory so that the status
information is available to you when you request it.

The function descriptions also explain that the GPIB-MAC “returns

to you” certain information. This means that the GPIB-MAC sends
information to you over the serial port. You then read this
information from your serial port

20

SECTION THREE - PROGRAMMING THE GPIB-MAC

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National Instruments

Serial Port Error Handling

The GPIB-MAC continuously monitors the serial port for transmis­sion errors. If it encounters an error in the serial data, the
MAC records the error. You can program the GPIB-MAC to stop
processing the programming message when a serial port error
occurs or to ignore these serial port errors. Refer to the spign
function.

GPIB-

GPIB Read

and’write

Termination Method (END

and EOS)

You program the GPIB-MAC to Talk in order to send data messages
over the GPIB, and to Listen in order to receive data messages from
the GPIB.

The IEEE-488 specification defines two ways that GPIB Talkers
and Listeners may identify the last byte of data messages: END and
EOS. The two methods permit a Talker to send data messages of

any length without the Listener(s) knowing in advance the number

of bytes in the transmission.

* END message

* EOS character

the Talker asserts the EOI (End or Identify)
signal while the last data byte is being
transmitted. The Listener stops reading when
it detects a data byte accompanied by EOI.

the Talker sends an EOS (end-of-string)
character at the end of its data suing. The
Listener stops receiving data when it detects
the EOS character. Either a ‘I-bit ASCII
character or a full

used.

g-bit

binary byte may be

The two methods can be used individually or in combination. It is

important that the Listener be configured to detect the end of a
transmission.

21

SECTION THREE - PROGRAMMING THE GPIB-MAC

November 1985

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National Instruments

The GPIB-MAC always terminates GPlB

rd

operations on the END
message. Using the eos and eot functions, you may change the
other default GPIB read and write termination methods.

Default Settings

The following tables list power-on characteristics of the GPIB-MAC
and the functions you can use to change those characteristics.

SERIAL PORT CHARACTERISTICS

Characteristic
echo bytes to serial port

ignore serial port errors
send

XON/XOFF

recognize

XON/XOFF

GPIB CHARACTERISTICS

Characteristic
primary/secondary address

end-of-string modes

Power-on Value
no

Yes

no
no

power-on Value

pad=O,sad=none

none
send END on writes
ist bit setting

yo”

GPIB-MAC is System Controller yes

I/O timeout

serial poll timeout

10

.l set

set

Function

echo
spign
xon
xon

Function

caddr

eos

cot

ist

IX
IlIlO
tIll0

List of Functions by Group

The

GPIBMAC

GPIB

functions, Serial Port functions, and General Use functions.

SECTION THREE - PROGRAMMING THE GPIB-MAC

22

functions are divided into three main groups:

November 1985

0

National Instruments

GPIB Functions

The

GPIB

functions are divided into subgroups as shown. The
subgroups are listed with the most frequently used groups first.
Often, the I/O and bus management functions are the only ones you

need.

I/O FUNCTIONS

Function
RD count,address

WRT count,address list

data

MANAGEMENT FUNCTIONS

BUS

Function

CLR address list
LOC address list
TRG address list

GPIB INITIALIZATION FUNCTIONS

Function

CADDR address

EOS modes,eoschar
EOT on/off

ONL on/off

RSC on/off

TM0

values

ti

Read data
write data

Pupose

Cl;;

sgzed

device(s)

Trigger selected device(s)

Puipose

Change the GPIB address
of the GPIB-MAC
Change/disable GPIB EOS
termination mode

Enable/disable END

message on

GPIBwrites

Place the GPIB-MAC online/

offline
Request or release System
Control
Change or disable time limit

SECTION THREE - PROGRAMMING THE

23

GPIEbMAC

November 1985

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National Instruments

SERIAL POLL FUNCTIONS

Function

RSP

address list

RSV

status byte

LOW-LEVEL CONTROLLER FUNCTIONS

Function

CAC mode
CMD count

commands

GTS mode
PCT address

SIC time
SRE on/off

PARALLEL POLL

Purpose
Request (conduct) a serial poll

Request service and/or set or

change the serial poll status
byte

Pur_Dose

Become active controller
Send IEEE-488 commands

Go from Active Controller to
Standby
Pass Control

Send interface clear
Set/clear remote enable

FUNCTIONS

Function

IST on/off

Purpos!2

Set or clear individual status
bit for use in GPlB-MAC

response to Parallel Polls
PPC values
PPU address list
RPP

Parallel Poll Configure

Parallel Poll Unconfigure

Request (conduct) a Parallel

Poll

SECTION THREE - PROGRAMMING THE GPIB-MAC

24

November 1985

Serial Port Functions

SERIAL PORT INITIALIZATION FUNCTIONS

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National Instruments

Function

ECHO

SPIGN on/off

XON modes

on/off

Purpose

Echo characters received from

serial port
Ignore serial port errors
Change serial port

XON/XOFF protocol

General Use Functions

GENERAL USE

Function

IDMAC
STAT modes
WAIT mask

FUNCTIONS

Purpwl

Identify system

Return GPIB-MAC status

Wait for selected event

List of Functions in Alphabetical Order

The following is an alphabetical list of all functions.

GPIB-MAC FUNCTIONS

Function

CAC mode
CADDR address

CLR address list

CMD count

commands

ECHO on/off

25

SECTION THREE - PROGRAMMING THE GPIB-MAC

m

Become active controller
Change GPIB address of the
GPIB-MAC
Clear specified device(s)
Send

GPIB

Echo characters received from
serial port

commands

November 1985

GPIB-MAC FUNCTIONS (CONTINUED)

0

National Instruments

EOS modes,eos
EOT on/off
GTS mode
IDMAC

IST set/clear

LOC address list

ONL on/off

PCT address
PPC values
PPU address list
RD count,address
RPP

RSC on/off
RSP address list

RSV serial poll
SIC time

SPIGN on/off

SRE on/off
STAT modes

TM0

values
TRG address list
WAIT mask
WRT count,address list

data

XON modes

Change/disable GPIB EOS
termination mode
Enable/disable END
message on

GPIB

writes
Go from Active Controller to
Standby
Identify system
Set or clear individual status
bit for use in GPIB-MAC
response to Parallel Polls
Go to Local
Place the GPlB-MAC
online/offline
Pass Control
Parallel Poll Configure
Parallel Poll Unconfigure
Read data
Request (conduct) a Parallel
Poll
Request or release System

Control
Request (conduct) a serial poll
Request service/set or change
the serial poll status byte

Send interface clear

Ignore serial port errors

Set or clear remote enable

Return GPIB-MAC status

Change or disable time limit

Trigger selected device(s)
Wait for selected event
write data

Change serial port

XON/XOFF protocol

26

SECTION THREE - PROGRAMMING THE GPIB-MAC

November 1985

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National Instruments

Section Four - Functions

This section contains descriptions of functions which you use to
program the GPIB-MAC. These functions are in alphabetical order

and are formatted to provide you a handy reference.

Points to Remember

1.

The programming examples for each function description are in
Microsoft BASIC version 2.0.

2.

In the syntax portion of the function descriptions, arguments
enclosed in brackets are optional. Do not enter the brackets as
part of your argument.

3.

Terminate each programming message with a catriage return

(<CR>), a linefeed

linefeed (<CR><LF>).

the syntax portions of the function descriptions. In the program-

ming examples, the BASIC PRINT # statement automatically

sends a carriage return at the end of the string, so a carriage
return is not placed there explicitly.

(<IF>),

or a carriage return followed by a

The terminator is denoted by

<CR>

in

4.

To send more than one programming message per PRINT

statement, embed a <CR> (denoted by

(denoted by CHR$( 10))in the statement. For example, to send

the two programming messages “send interface clear” and “send

remote enable,” you could use either of these two sequences:

PRINT #l,“sic”
PRINT

PRINT # 1

5.

For all examples, the communications port has been assigned to

file number 1

27

SECTION FOUR - FUNCTIONS

#l,“sre

or

(#l)

by the BASIC OPEN

1”

,“sic”+CHR$( 13)+“sre

CIIR$(

“COM...”

13)) or

1”

statement.

<LF>

November 1985

6.

It is necessary for you to send only enough characters of the

0

National Instruments

function name to distinguish it from other functions. Those
characters are shown in boldface in the syntax portion of each
function description.

‘7.

I/O and bus management functions meet most of your needs. In
the descriptions that follow, these frequently used functions are
marked with an asterisk

(*).

28

SECTION FOUR - FUNCTIONS

November 1985

cat -

Become Active Controller

cat:

Low-level Controller function

0

National Instruments

Syntax:

Purpose:

Remarks:

cat

[bool]cCR>

You use
Controller to Active Controller and when the I/O and bus
management functions do not meet the needs of your
device.
GPIB than the I/O and bus management functions.

If the argument
immediately; that is, it takes control asynchronously. If
the argument

after any handshake that is in progress completes; that is,
it takes control synchronously.

If you call

returns to you the current controller status, which is 0 if

the GPIB-MAC is m the Active Controller
GPIB-MAC h the Active Controller.

If call
CIC, the GPIB-MAC records the ECIC error.

The power-on Controller status of the GPIB-MAC is
Idle Controller.

cat

to change the GPIB-MAC from Standby

cat

allows you more precise control over the

boo1

is 1, the GPIB-MAC takes control

boo1

is 0, the GPIB-MAC takes control

cat

without an argument, the GPIB-MAC

and1

if the

cat

with an argument and the GPIB-MAC is not

Refer also to

29

SECTION FOUR - FUNCTIONS

gts

and sic.

November 1985

Examples:

0

National Instruments

1.

PRINT#l,“cac

PRINT # 1

2.

1”

,“cac 0”

3. PRINT #l,“CAC”

response:

lcCRxLF>

‘Take control immediately.

‘Take control synchronously.

‘Are we the active controller?

.

..yes...we’re

CAC

SECTION FOUR - FUNCTIONS

30

November 1985

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National Instruments

caddr

cad&

Syntax:

Purpose:

Remarks:

-

Change GPIB Address of the GPIB-MAC

Initialization function

cad&

You use
change the GPIB address of the GPIB-MAC.

The argument
new GPIB address for the GPIB-MAC. addr consists
of a primary address and an optional secondary address.
The secondary address is separated from the primary
address by a plus sign
expressed as numeric strings.

Only the lower five bits of each address are significant.
These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

[addr]&R>

caddr

at the beginning of your program to

addr

is a device address that specifies the

(+).

Both addresses are

0+2

If you specify a primary address without a secondary
address, secondary addressing is disabled.

If you call caddr without an argument, the GPIB-MAC

returns to you its current GPIB address.

The address assigned by this function remains in effect
until you call caddr again, call onl, or you turn off the
GPIB -MAC.

31

SECTION FOUR - FUNCTIONS

or

0+98

or

32+98

or

O+\x62

November 1985

The power-on default is 0 with secondary addressing
disabled.

Examples:

0

National Instruments

1~

PRINT

2. PRINT

3. PRINT #l,“CADDR”

response:

#l,“caddr 0+22”

#l,“CADDR

lcCRxLF>

1”

‘Give GPIB-MAC a primary address
‘of 0 and a secondary address of 22.

‘Change GPIB-MAC primary
‘address to 1 and disable secondary
‘addressing.

‘Return current GPIB-MAC address.

SECTION FOUR - FUNCTIONS

32

November 1985

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National Instruments

clr - Clear. Specified Device

Bus

Clr:

Syntax:

Purpose:

Remarks:

Management function
clr [alist]cCR>
You use

the specified devices. For example, a multimeter might
require that you send it either the GPIB Device Clear or
Selected Device Clear command to change its function,
range, and trigger mode back to its default setting. Use
clr to do this.

The argument

commas or spaces. addrs are device addresses that

specify the GPIB addresses you wish to clear. alist

may consist of only one addr.
A device address consists of a primary address and an

optional secondary address. The secondary address is

separated from the primary address by a plus sign
Only the lower five bits of each address are significant

These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,

the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

clr

to reset the internal or device functions of

alist

is a list of addrs separated by

*

(+).

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is
or 98, which are equivalent.

0+2

If you call
devices specified in

If you call

devices (Device Clear).

33

SECTION FOUR - FUNCTIONS

clr

clr

or

0+98

or

32+98

with

alist, the GPIB-MAC

alist

(Selected Device Clear).

without

alist, the GPIB-MAC

or

O+\x62

clears only the

clears all

November 1985

If this is the first function you call that requires GPIB

controller capability, and you have not disabled System
Controller capability with csc, the GPIB-MAC sends
Interface Clear
Remote Enable.

Refer to Appendix D for more information on clearing
devices.

Refer to Appendix B for more error information.

Examples:

0

National Instruments

(IX)

to make itself CIC. It also asserts

1. PRINT

#l,“clr 14+30,16+12,18,3+26,6”

2. PRINT #l,“CLR”

*

frequently used function

‘Selectively clear

‘5 devices.

‘Issue Device Clear
‘to all devices.

34

SECTION FOUR - FUNCTIONS

November 1985

cmd - Send GPIB Commands

cm&

Specialized Controller function

0

National Instruments

Syntax: cmd

Purpose:

Remarks:

[#count]<CR>

commands<CR>

You

use

cmd

when the I./O and bus management

functions do not meet the needs of your device.

allows you precise control over the GPIB. For example,
in applications that require command sequences not sent
by other functions,
sequence of interface messages (commands) over the

GPIB .

The argument
number sign
command bytes (interface messages) to send, which is a
number between 1 and 255. The number of command
bytes must not include the carriage return or
you include to indicate the end of the programming
message.

The argument
These commands are represented by their ASCII
character equivalents. For example, the GPIB Untalk

(UNT)

Refer to Example 2 to learn how to send non-printable
characters.

command is the ASCII character underscore C).

cmd allows you

count

(#).

commands

is a numeric string preceded by a

#count specifies the number of GPIB

is a list of GPIB commands.

to transmit any

cmd

linefeed

that

If you call
recognizes the end of the command string when it sees
a

<CR>

command string contains a
However, a
would be unusual since neither of these is a defmed
GPIB command.

SECTION FOUR - FUNCTIONS

35

or

cmd

<LF>.

<CR>

without

#count, the

GPIB-MAC

#count is required only if the

<CR>

or an

(LF>

or an

d3;>

in the command string

character.

November 1985

The GPIB commands, or interface messages, are listed
in Appendix A. They include device talk and listen

addresses, secondary addresses, messages, device clear
and trigger instructions, and other management

messages.

0

National Instruments

Do not use

cmd

to send programming instructions to

devices. Use rd and wrt to send or receive device
programming instructions and other device dependent

information.

The cmd

-

-

operation terminates when:
the GPIB-MAC successfully transfers all commands,
the GPIB-MAC detects an error (GPIB-MAC is not

CIC),

-

the

I/O

time

limit

is exceeded,

-

the Take Control

(TCT)

command is in your

command string and is sent to the GPIB.

-

the Interface Clear

(IX)

message is received from

System Controller (not the GPIB-MAC).

After cmd terminates, the GPIB-MAC records the
number of command bytes it actually sent.

If an event in
the above list occurs, the count may be less than
expected

36

If you specify #count and enter more than #count
command bytes, the excess command bytes up to the

<CRXLP>

are discarded.

If you call cmd and the GPIB-MAC is not CIC, the

GPIBMAC

SECTION

FOUR -

records the ECIC error.

FUNCTIONS

November 1985

If the GPIB-MAC is CIC but not Active Controller, it
takes control and asserts ATN before sending the
command bytes. It remains Active Controller afterward.

Refer to Appendix A to convert hex values to ASCII
characters.

Examples:

0

National Instruments

1. PRINT

#l,“cMD”

‘Program device at address 11 to
‘listen and GPIB-MAC at address 0
‘to talk.

PRINT #l,“+@”

‘Device listen address is 43 or
‘ASCII + and GPIB-MAC talk

‘address is 64 or ASCII
PRINT # 1,’
PRINT # 1

,‘I ABCDE”

‘WI-W

Write the string
‘device at address 11.

2. PRINT #l,“cmd”-tCHR$(13)+”
‘Pass control to device 23

‘(CHR$(9)=TCT

“ABCDE”

?W”+CHR$(9)

command).

@.

to

37

SECTION FOUR - FUNCTIONS

November 1985

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National Instruments

echo - Echo Characters Received from Serial

Port

echo:

Syntax:

Purpose:

Remarks:

Examples:
Note:

1. echo

The following examples show commands as you would
enter them at a terminal.

Serial Port function

echo [bool]<CR>

You use
on the Macintosh while connected to the GPIB-MAC and

you wish to echo what you type on the screen.

If the argument
serial port are echoed back to the serial port
argument
argument
disabled, characters will not be echoed until this
command has been completely processed, i.e., the
programming message will be echoed

If you call echo without an argument, the GPIB-MAC
returns the current setting.

l&R>

echo

when a terminal emulation program is run

boo1

is 1, characters received from the

If the

boo1

is 0, characters are not echoed. If the

boo1

is 1 and echoing was previously

Turn on character echoing.

m

2. ECHO O<CR>

3.

echo&R>

response:

38

SECTION FOUR - FUNCTIONS

OcCRxLF>

‘Disable character echoing.

What is the current echo status?

(character echo is disabled)

0

November 1985

National Instruments

eos - Change/Disable GPIB EOS Termination

Mode

eos: Initialization function

Syntax: eos [[R][X][B] eoschar]<CR>

or

eos D<CR>

Purpose:

Remarks:

You use eos at the beginning of your program if you
wish to use an eos mode when you transfer data to and
from the GPIB. eos tells the GPIB-MAC when to stop
reading information from the
the GPIB-MAC to tell other devices that it is finished
writing information to the GPIB. eos defines a specific
character, end-of-string (EOS), to be recognized as a

string terminator.
The arguments R, X, B, and D specify GPIB termin-

ation methods. They enable or disable the corresponding
eos mode. If a particular letter is specified, the corres-

ponding eos mode is enabled. If it is not specified, the

corresponding eos mode is disabled.
eoschar is a numeric string which represents a single

ASCII character. For example, 10 represents the ASCII

linefeed character.

DATA TRANSFER TERMINATION METHODS

pescrintioq

REOS - terminate read when EOS is detected.

GPIB.

eos also enables

Letter

R
XEOS - set EOI with EOS on write functions. X
BIN - compare all 8 bits of EOS byte rather than

low 7 bits (all read and write functions).

DISABLE - disable all eos modes.

39

SECTIONFOUR-FUNCTIONS

B

D

November 1985

Methods R and B determine how GPIB read operations
performed by the GPIB-MAC terminate. If Method R
alone is chosen, reads terminate when the low 7 bits of
the byte that is read match the low 7 bits of the EOS
character. If Methods R and B are chosen, a full
comparison is used.

Methods X and B together determine when GPIB write
operations performed by the GPIB-MAC send the END
message. If Method X alone is chosen, the END
message is sent automatically with the EOS byte when
the low 7 bits of that byte match the low 7 bits of the
EOS character. If Methods X and B are chosen, a full

g-bit comparison is used.

Note that defining an EOS byte for the GPIB-MAC does
not cause the GPIB-MAC to insert that byte into the data
string when performing GPIB writes. To send the EOS
byte, you must include it in the data string that you send
following the

By default, no eos modes are enabled.

wrt

programming message.

0

National Instruments

g-bit

If you call

eos

MAC records the EARG error.

If you call eos without an argument, the GPIB-MAC
returns to you the current eos settings.

The assignment made by this function remains in effect
until you call eos again, call
GPIB-MAC.

Refer to the GPIB Read and Write Termination
explanation in Section Three.

40

SECTION FOUR - FUNCTIONS

with B alone as an argument, the GPIB-

onl,

or you turn off the

November 1985

Examples:

0

National Instruments

1.

PRINT

#l,“eos R,B,lO”

‘Terminate read when
‘detected; compare all 8 bits; do
‘not send EOI with

PRINT

#l,“rd

10

5”

‘Read 10 bytes from device 5 into
‘serial port buffer.

RESP$=INPUT$( lO,#l)

‘Input 10 bytes from serial port

‘buffer.
LINE INPUT #l,COUNT$

CNT%=VAL(COUNT$)

PRINT COUNT$;“bytes were read from

‘Input string that indicates number

‘of bytes actually read from GPIB

‘of bytes that were read from the

‘GPIB.

2. PRINT

#l,“EOS X,13”

‘Tell GPIB-MAC on wrt, send

‘EOI

‘terminate when <CR> is

‘detected; compare 7 bits.
PRINT

#l,“wrt #lO 5”

‘GPIB-MAC sends EOI with

‘<CR> (CHR$(13))

‘listeners that this is the last byte

‘of data.

PRINT

#1,“012345678”+CHR$(13)

with

GPKB”

<CR>;

<LF>

is

<LF>.

‘Print number

on rd, do not

to tell

3. PRINT #l,“eos”

response:

41

SECTION

X,13cCRxLF>

FOUR -

‘What are the current EOS
‘settings?

FUNCTIONS

0

November 1985

National Instruments

eot - Enable/Disable END Message on GPIB

Writes

cot:

Initialization function

eot[

boo11

Syntax:

<CR>

Purpose:

Remarks:

You use eot at the beginning of your program if you
wish to change how the GPIB-MAC terminates GPIB
writes. Using eot, you tell the GPIB-MAC to auto­matically send or not send the GPIB END message with
the last byte that it writes to the GPIB.

If the argument
sends the END message with the last byte of each
If the argument
on default is 1.

If you call eot without an argument, the GPIB-MAC
returns to you a 1 to indicate END termination is
currently enabled, or a 0 to indicate END termination is
currently disabled

The assignment made by
call eot again, call onl, or you turn off the GPIB-MAC.

The GPIB-MAC sends the END message by asserting
the GPIB EOI signal during the last byte of a data
transfer. eot is used primarily to send variable length
data.

Refer to the GPIB Read and Write Termination
explanation in Section Three.

boo1

is 1, the GPIB-MAC automatically

boo1

is 0, END is not sent. The

eot

remains in effect until you

wrt.

power-

SECTION FOUR - FUNCTIONS

42

November 1985

Examples:

0

National Instruments

1. PRINT

2. PRINT
PRINT
PRINT #

#l,“eot 0”

#l,“EOT

#l,“WRT

1,”

ABCDE”

3. PRINT #l,“eot”

response:

lcCRxLF>

1”

3”

‘Disable END termination.

‘Send END with last byte.
Write data to device at address 3.
The EOI line is automatically
‘asserted when the last byte (the

letter E) is sent to tell the

‘Listeners it is the last byte of data.

What is the current EOT setting?

(END termination is currently

enabled)

43

SECTION FOUR - FUNCTIONS

November 1985

0

National Instruments

gts - Go from Active Controller to Standby

gts: Specialized Controller function

Syntax: gts [bool]cCR>

Purpose:

Remarks:

You use
Controller to Standby Controller. You use gts when the

I/O and bus management functions do not meet the needs

of your device. For example, you use gts if you wish to

allow two external devices to talk to each other directly.

The GPIB-MAC can selectively participate in the hand-

shake of the data transfer and hold off the handshake
when it detects the END message. The GPIB-MAC can
then take control synchronously without possibly
corrupting the transfer.

If the argument
enabled. If the argument
handshaking is not performed.

If you call gts without an argument, the GPIB-MAC

returns to you the current controller status: CSB,O if the

GPIB-MAC is in Standby without shadow handshaking;

CSB,l

handshaking; CAC if the GPIB-MAC is CIC but is not
in Standby, i.e., it is the Active Controller; and
the GPIB-MAC is not the CIC, i.e., is an IDLE
Controller.

gts causes the GPIB-MAC to go to the Controller
Standby state and to unassert the ATN signal if it is
initially the Active Controller. gts permits
devices to transfer data without the GPIB-MAC

participating in the transfer.

gts

to change the GPIB-MAC from Active

boo1

is 1, shadow handshaking is

boo1

is 0, shadow

if the GPIB-MAC is in Standby with shadow

COLE

GPIB

if

44

SECTION FOUR - FUNCTIONS

November 1985

If you enable shadow handshaking, the GPIB-MAC
participates in the data handshake as an Acceptor without
actually reading the data It monitors the transfers for the
END (EOI or end-of-string character) message and holds
off subsequent transfers. This mechanism allows the

GPIB-MAC to take control synchronously on a
subsequent operation such as

Before performing a gts with a shadow handshake, you
should call eos to establish the proper end-of-string
character or to disable the EOS detection if the
string character used by the talker is not known.

If you call gts with an argument and the GPIB-MAC is
not CIC, the GPIB-MAC records the ECIC error.

0

National Instruments

cmd

or

rpp.

end-of-

Refer also to

Examples:

1.

PRINT

2. PRINT

3. PRINT #l,“gts”

response:

#l,“gts 0”

#l,“GTS

CSB,lcCRxLF>

cat.

‘GTS without shadow handshaking.

1” ‘GTS with shadow handshaking.

What is the standby status?

(GPIB-MAC is in standby

status with shadow
handshaking)

45

SECTION FOUR - FUNCTIONS

November 1985

0

National Instruments

idMAC -

idMAC:

Syntax: idMAC<CR>

Purpose:

Remarks:

Example:

PRINT # 1

response: GPIB-MAC, Rev.

Identify System

General Use function

You use
of your software, or if you wish to know how much

RAh4

The identification is returned in three strings. The first
two strings identify the company product model, the
software revision level, and a copyright notice. The
third string identifies the number of bytes of RAM in the
GPIB-MAC.

idMAC if you

is installed in your GPIB-MAC.

,“idhIAC”

(c)1985 National

2K bytes

RAMcCR>cLF>

wish to know the revision level

‘Get system identification

A.OcCRxLF>

InstrumentscCR>cLF>

SECTION FOUR - FUNCTIONS

46

November 1985

0

National Instruments

ist - Set or Clear Individual Status Bit

ist:

Parallel Poll function

Syntax:

Purpose:

Remarks:

Examples:

1. PRINT

2. PRINT

3. PRINT #l,“ist”

ist

[bool]&R>

You use ist when the GPIB-MAC participates in a
parallel poll that is conducted by another device that is
Active Controller.

If the argument
status bit is set to 1. If the argument
GPIB-MAC’s individual status bit is cleared. The
power-on default is 0.

If you call ist without an argument, the GPIB-MAC
returns the value of its individual status bit.

Refer also to

#l,“ist

#l,“IST 0”

1”

boo1

is 1, the GPIB-MAC’s individual

ppc

and Appendix F.

‘Set ist to 1.

‘Clear ist to 0.

‘What is ist set to?

boo1

is 0, the

response:

SECTION FOUR - FUNCTIONS

47

OcCR>cLF>

(ist is currently 0)

November 1985

lot -

Go to Local

lot: Bus Management function

lot

[

alist]

Syntax:

<CR>

0

National Instruments

*

Purpose:

Remarks:

You use

this mode you can program the device from its front

panel.

program mode before it can be programmed from the
GPIB, the GPIB-MAC automatically puts the device in
remote program mode. You then use
devices to local program mode.

The argument
commas or spaces.
specify the GPIB addresses of the devices you wish to
return to local mode.

A device address consists of a primary address and an
optional secondary address. The secondary address is
separated from the primary address by a plus sign

Only the lower five bits of each address are significant
These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of

0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

lot

to put a device in local program mode. In

Since a device must usually be placed in remote

lot

to return

alist

is a list of

addrs are

addrs

separated by

device addresses that

(+).

0+2

If you call
specified device(s) in local mode using the Go To
Local (GTL) command

SECTION FOUR - FUNCTIONS

48

lot

or

with

0+98

or

32+98

alist,

the GPIB-MAC places the

or

O+\x62

November 1985

If this is the first function you call that requires GPIB

controller capability, and you have not disabled System
Controller capability with
Interface Clear

Remote Enable. If you passed control to some other

GPIB device, control must be passed back to you or you
must send IPC to make yourself CIC before making this
call. Otherwise, the ECIC error will be posted.

0

National Instruments

rsc,

the GPIB-MAC sends

(IX)

to make itself CIC. It also asserts

If you

call~loc

System Controller, the GPIB-MAC returns all devices
to local mode by unasserting REN and asserting it
again. If you call
MAC is not System Controller, the GPIB-MAC records
the ESAC error.

Refer to Appendix B for more error information.

Examples:

1. PRINT

2. PRINT

#l,“loc 6+22,4+23,7”

#l,“LOC’

* frequently used function

without

lot

without

alist,

and the GPIB-MAC is

alist

and the GPIB-

‘Put 3 devices in local mode.

‘Put all devices in local mode.

49

SECTION FOUR - FUNCTIONS

0

November 1985

on1 -

Place the GPIB-MAC Online/Offline

onl: Initialization function

National Instruments

Syntax:

Purpose: You use

Remarks:

on1

[bool] <CR>

GPIB-MAC and the GPIB, or to reinitialize the GPIB-
MAC characteristics to their default values.

If the argument

online. If the argument

places itself offline. By default, the GPIB-MAC powers

up online, is in the Idle Controller state, and configures
itself to be the System Controller.

If you call
returns the current status of the GPIB-MAC, which is 0
if the GPIB-MAC is offline and 1 if the GPIB-MAC is
online.

Placing the GPIB-MAC offline may be thought of as
disconnecting its GPlB cable from the other GPIB
devices.

Placing the GPIB-MAC online allows the GPIB-MAC to
communicate over the GPIB, and also restores all GPIB-
MAC settings to their power-on values.

on1

to disable communications between the

boo1

is 1, the GPIB-MAC places itself

boo1

is 0, the GPIB-MAC

on1

without an argument, the GPIB-MAC

Refer to the Serial Port Characteristics table and the
GPIB Characteristics table in Section Three for the
GPIB-MAC power-on settings.

50

SECTION FOUR - FUNCTIONS

November 1985

Examples:

0

National Instruments

1. PRINT

2. PRINT

#l,“onl

1”

#l,“ONL 0”

‘Put the GPIB-MAC online and
‘restore its power-on settings.

‘Put the GPIB-MAC offline to
‘prevent it from communicating
‘with the GPIB.

51

SECTION FOUR - FUNCTIONS

November 1985

pet

- Pass Control

pet: Specialized Controller function

0

National Instruments

Syntax: pet

Purpose:

Remarks:

addr<CR>

You use

pet

to pass Controller-In-Charge (CIC)

authority from the GPIB-MAC to some other device.
The argument

addr

is the address of the device you wish

you wish to pass control to. addr consists of a primary

address and an optional address. The secondary
address is separated from the primary address by a plus
sign

(+).

Both address are expressed as numeric strings.

Only the lower five bits of each address are significant.
These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of

0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

0+2

or

0+98

or

32+98

or

O+\x62

pet

passes CIC authority from the GPIB-MAC to the

device specified by addr. The GPIB-MAC auto­matically goes to Controller Idle State. It is assumed that
the target device has Controller capability.

If you call

pet

with an argument and the

not CIC, it records the ECIC error.
If you call

pet

without an argument, the GPIB-MAC

records the EARG error.

52 SECTIONFOUR-FUNCTIONS

GPIB-

MAC is

November 1985

Example:

0

National Instruments

PRINT

#l,“pct 7+18”

‘Pass control to device with
‘primary address 7 and
‘secondary address 18.

53 SECTIONFOUR-FUNCTIONS

November 1985

0

ppc - Parallel Poll Configure

Parallel Poll function

Ppc:

National Instruments

Syntax:

Purpose:

Remarks:

ppc addr,ppr,s [addr,ppr,s] [addr,ppr,s]...cCR>
You use

ppc

to configure specified devices to respond

to parallel polls in a certain manner.

addr

specifies the GPIB address of the device to be

enabled or disabled for parallel polls. addr consists of a

primary address and an optional secondary address. The

secondary address is separated from the primary address
by a plus sign

(+).

Both addresses are expressed as

numeric strings.
Only the lower five bits of each address are significant

These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

0+2

or

0+98

or

32+98

or

O+\x62

The argument
specifying the data line on which to respond.

The argument s is either 0 or 1 and is interpreted along
with the value of the device’s individual status bit to
determine whether to drive the line true or false.

Each group of addr,ppr,s may be separated by either a

comma or space, just as any list of arguments.

SECTION FOUR - FUNCTIONS

54

ppr

is an integer string between 1 and 8

November 1985

0

National Instruments

If you

call

ppc

without an argument, the GPIB-MAC

records the EARG error.

If this is the first function you call that requires GPIB
controller capability, and you have not disabled System
Controller capability with rsc, the GPIB-MAC sends
Interface Clear

(IFC)

to make itself CIC. It also asserts

Remote Enable.
If you passed control to some other GPIB device,

control must be passed back to you or you must send

IFC to make yourself CIC before making this call.
Otherwise, the ECIC error will be posted.

The GPIB-MAC takes the arguments ppr and s and

constructs the appropriate parallel poll enable
message for each

addr

specified.

When addr is the address of the GPIB-MAC, the

(PPE)

GPIB-

MAC programs itself to respond to a parallel poll by
setting its local poll enable (lpe) message to the value

specified.

Refer also to ist, ppu, rpp, and to Appendix F on
parallel polling.

Example:

PRINT
PRINT # 1

#l,“PPC 18+23,8,0 23+10,7,1”

,“RPP”

response:192cCRxLF>

LINE INPUT #l ,RESP$

PPR%=VAL(RESP$)

55

SECTION FOUR - FUNCTIONS

‘Configure 2

‘devices for parallel poll.

‘Conduct a Parallel poll of 2
‘devices configured above.
(both devices responded

positively)

‘Assign parallel poll response to
‘integer variable.

November 1985

ppu -

Parallel Poll Unconfigure

ParaIlel Poll function

PPu :

0

National Instruments

Syntax:

Purpose:

Remarks:

ppu

[alist] <CR>

You use
you wish to prevent certain devices from responding.

The argument
separated by commas or spaces. addrs are device
addresses that specify the
or devices to be disabled from parallel polls.

A device address consists of a primary address and an
optional secondary address. The secondary address is
separated from the primary address by a plus sign

Only the lower five bits of each address are significant
These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,

the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

ppu

if you are performing parallel polls and

alist

is a list of addrs which are

GPIB

addresses of the device

(+).

0+2

If you call
from parallel polls only those devices specified in

If you call
unconfigures all devices from parallel polls.

56

SECTION FOUR - FUNCTIONS

ppu

ppu

or

0+98

with

alist,

without

or

32+98

or

O+\x62

the GPIB-MAC

alist,

the GPIB-MAC

unconfigures

alist.

November 1985

If this is the first function you call that requires GPIB
controller capability, and you have not disabled System
Controller capability with
Interface Clear
Remote Enable.

If you passed control to some other GPIB device,
control must be passed back to you or you must send
IFC to make yourself CIC before making this call.
Otherwise, the ECIC error will be posted.

0

National Instruments

rsc,

the GPIB-MAC sends

(IFC)

to make itself CIC. It also asserts

If the address of the GPIB-MAC is included in
GPIB-MAC disables itself from responding to parallel
polls.

Refer also to ist,
parallel polls.

Examples:

1. PRINT

#l,“ppu

14”

2. PRINT #l,“PPU”

alist,

the

ppc, rpp,

and to Appendix F on

‘Send the PPU command to device 14.

‘Send the PPU command to all devices.

57

SECTION FOUR - FUNCTIONS

November 1985

0

National Instruments

rd - Read Data

rd:

I/O function

Syntax: rd #count

Purpose:

Remarks:

You use rd to read data from the GPIB.
The argument #count is a numeric string preceded by a

number sign
to read. count must not contain a comma. It can
specify a number between 1 and 65535.

The argument
address of the device to be addressed as a Talker. addr
consists of a primary address and an optional secondary
address. The secondary address is separated from the
primary address by a plus sign

Only the lower five bits of each address are significant
These bits may be in the range from 0 through 30 for

both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

*

[addr]<CR>

(#).

#count specifies the number of bytes

addr

is a device address that specifies the

(+).

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

The GPIB-MAC reads data from the GPIB until the
specified byte count is reached, the GPIB END message
is received with a data byte, the EOS byte is received, or
a timeout occurs.

Refer also to eos, eot, and tmo.

58

SECTION FOUR - FUNCTIONS

0+2

or

0+98

or

32+98

or

O+\x62

November 1985

Because you may not know for certain the number of
bytes actually read from the GPIB, the GPIB-MAC
returns the received GPIB data to you as follows. First,
the GPIB-MAC returns to you all bytes it read from the
GPIB. Next, it sends null bytes until the total number of
bytes returned to you matches your requested count.
Finally, it returns a numeric string representing the
number of bytes that it actually read from the GPIB.

For example, if you send the GPIB-MAC the pro­gramming message “rd
GPIB until it receives 10 bytes of data, the END
message, or an eos byte. Let’s say the GPIB-MAC
receives END with the fourth data byte. The GPIB-
MAC then returns to you the four data bytes, followed
by 6 null bytes, followed by an ASCII 4 and

<CR>&F>.

always read back count bytes of data from the serial
port, then look at the remaining bytes to determine how
many of the count bytes were read from the GPIB.
Refer to the example at the end of this description.

0

National Instruments

lO”<CR>,

it reads data from the

A null byte is decimal 0. You should

59

The GPIB-MAC aborts the GPIB read and records the
EABO error if, at any time during the GPIB read, the
time limit set for I/O functions expires. This limit is 10
seconds unless you use

If the GPIB-MAC is CIC, rd will cause the GPIB-MAC
to address itself to Listen if it is not already addressed.
If you specify the address of the Talker, the GPIB-MAC
will also address that device to Talk.
specify the address of the Talker, the GPIB-MAC will
assume that the Talker has already been addressed.

The GPIB-MAC then places itself in Standby Controller
state with ATN off and remains there after the read
operation is completed

If you specify an address, the GPIB-MAC must be CIC
to perform the addressing.

SECTION

FOUR -

FUNCTIONS

tmo

to change it.

If you do not

November 1985

0

National Instruments

If this is the
controller capability, and you have not disabled System
Controller capability with rsc, the GPIB-MAC sends
Interface Clear
Remote Enable.

If you passed control to some other GPIB device,
control must be passed back to you or you must send

IPC to make yourself CIC before making this call.

Otherwise, the ECIC error will be posted.

If

the GPIB-MAC is not CIC and you do not specify the
talker address, the GPIB-MAC assumes it will be
addressed by the Controller, then proceeds.

If you call rd without an argument, the GPIB-MAC
records the EARG error.

Refer also to tmo.

Example:

PRINT

#l,“rd

#lO 3”

RESP$=INPUT$( lO,#l)
LINE INPUT #l,COUNT$

COUNT%=VAL(COUNT$)

fust

function you call that requires GPIB

(IFC)

to make itself CIC. It also asserts

Read up to 10 bytes from the
‘GPIB device at address 3.
‘Input 10 bytes from serial port
‘buffer.
‘Input ASCII string representing
‘number of bytes read from the
‘GPIB.
‘COUNT% is number of bytes
‘read from GPIB; remaining bytes
‘in RESP$ may be ignored.

* frequently used function

60

SECTION FOUR - FUNCTIONS

November 1985

0

National Instruments

rPP -

Syntax:

Purpose:

Remarks:

Request (Conduct) a Parallel Poll

rpp: Parallel Poll function

rppcCR>

You use rpp if

obtain information from several devices at the same time.

rpp causes the GPIB-MAC to conduct a parallel poll of
previously configured devices by sending the IDY
message (ATN and EOI both asserted) and reading the
response from the GPIB data lines. The GPIB-MAC
pulses the IDY message for greater than or equal to 2
microseconds and expects valid responses within that
time. It remains Active Controller afterward

The GPIB-MAC returns the Parallel Poll Response

(PPR) following the poll in the form of a numeric string

representing the decimal value of the response.
If this is the first function you call that requires GPIB

controller capability, and you have not disabled System
Controller capability with
Interface Clear
Remote Enable.

you wish to conduct a parallel poll to

rsc,

the GPIB-MAC sends

(IFC)

to make itself CIC. It also asserts

If you passed control to some other GPIB device,
control must be passed back to you or you must send
IFC to make yourself CIC before making this call.
Otherwise, the ECIC error will be posted.

Refer also to ist,

parallel polls.

61

SECTION FOUR - FUNCTIONS

ppc, ppu,

and to Appendix F on

November 1985

Example:

0

National Instruments

PRINT

response:

LINE INPUT

#l,“ppc 13,1,0 15,3,O”+CHR$(13)+“rpp”

ScCRxLF>

#l,RESP$

PPR%=VAL(RESP$)

PRINT # 1,’

‘ppu”

‘Configure 2
‘devices for parallel polls and poll
‘them.

(both devices responded positively)

‘Get parallel poll response from
‘serial port buffer and assign it to
‘integer variable PPR%.

‘&configure all devices from

‘parallel polls.

62

SECTION FOUR - FUNCTIONS

0

November 1985

National Instruments

rsc - Request or Release System Control

Initialization function

rsc:

rsc

Syntax:

[bool] <CR>

Purpose:

Remarks:

You use rsc if some other device in your GPIB system
should be System Controller.

If the argument

itself to be the GPIB System Controller. If the argument

boo1

is 0, the GPIB-MAC configures itself as not

System Controller.
If you call

returns to you its System Controller status, which is 0 if
GPIB-MAC is not currently System Controller or 1 if the
GPIB-MAC is System Controller.

As System Controller the GPIB-MAC can send the Inter­face Clear

GPIB devices. If some other Controller asserts Interface
Clear, the GPIB-MAC cannot respond unless it is
configured as not System Controller.

In most applications, the GPIB-MAC will be System
Controller. In some applications, the GPIB-MAC will
never be System Controller. In either case, rsc is

used only if the Macintosh is not going to be System

Controller while the program executes. The IEEE-488

standard does not specifically allow schemes in which

System Control can be passed from one device to an-

other, however,

boo1

is 1, the GPIB-MAC configures

rsc

without an argument, the GPIB-MAC

(IX)

and Remote Enable @EN) messages to

rsc

could be used in such a scheme.

The GPIB-MAC configures itself to be System Control-

ler at power-on.

Refer also to sic and sre.

SECTION FOUR - FUNCTIONS

63

November 1985

Examples:

0

National Instruments

1. PRINT

2. PRINT

#l,“rsc

#l,“rsc 0”

3. PRINT #l,“rsc”

response:

OcCR>cLF> (GPIB-MAC is not the System

1”

‘Enable GPIB-MAC to be system
‘controller.

‘Disable system control.

What is the current system
‘controller status?

Controller)

64

SECTION

FOUR -

FUNCTIONS

November 1985

0

National Instruments

rsp - Request (Conduct) a

Serial Poll function

rsp:

rsp

Syntax:

Purpose:

Remarks:

al&&R>

You use
device-specific status information from one or more
devices.

The

by commas or spaces.
specify the GPIB addresses you wish to poll.

A device address consists of a primary address and an
optional secondary address. The secondary address is
separated from the primary address by a plus sign

Only the lower five bits of each address are significant.
These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of

0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2

,or

rsp if you

argument

wish to conduct a serial poll to obtain

alist

is a list of addrs which are separated

addrs are

98, which are equivalent.

Serial Poll

device addresses that

(+).

0+2

rsp

serially polls the specified devices to obtain their

status bytes.
device’s response is set, its status response is positive,
i.e., that device is requesting service. Before rsp
completes, all devices are unaddressed.

65

SECTION FOUR - FUNCTIONS

or

0+98

or

32+98

or

O+\x62

If bit 6 (the hex 40 or RQS bit) of a

November 1985

The interpretation of each device’s response, other than
the RQS bit, is device specific. For example, the polled
device might set a particular bit in the response byte to
indicate that it has data to transfer, and another bit to
indicate a need for reprogramming. Consult the device
documentation for interpretation of the response byte.

Each device’s serial poll response byte is returned as a
numeric string giving the decimal value of the byte,
followed by
respond in the timeout period, the GPIB-MAC returns

string -1 and records the EABO error. The time limit is
set to

Each response corresponds directly to an address you

specify, therefore, there are exactly as many lines of

responses, including - 1, as the number of addresses you

specify.

0

National Instruments

<CR>

and

<LF>.

l/l0

second unless you called

If a device does not

tmo

to change it.

If you call

rsp

attempts to become CIC. If it cannot become CIC, it
records the ECIC error. Refer to Appendix B for more
information.

If this is the first function you
controller capability, and you have not disabled System
Controller capability with rsc, the GPIB-MAC sends
Interface Clear
Remote Enable.

If you passed control to some other GPIB device,

control must be passed back to you or you must send

IFC to make yourself CIC before making this call.

Otherwise, the ECIC error will be posted.

If you call

rsp

records the EARG error.

Refer also to

66

SECTION FOUR - FUNCTIONS

and the GPIB-MAC is not CIC, it

caIl

that requires GPIB

@FC)

to make itself CIC. It also asserts

without an argument, the GPIB-MAC

tmo

for timeout information.

November 1985

Example:

0

National Instruments

PRINT

response:

#l,“rsp 1+28,5,9”

42cCRxLF>
30cCR>cLF>

‘Poll 3 devices.

(device 9 did not respondwithin

the timeout period)

-lcCR><LF>

DBlSPR%(2)

FOR I=0 to 2

LINE INPUT #l ,RESP$

SPR%(I)=VAL(RESP$)

IF SPR%(I) = -1 THEN

NEXT1

REM Code will now interpret serial poll responses.

Read 3 responses from serial port
‘buffer.

‘Store each serial poll response in
‘the array SPR%.

GOSUB

1000 ‘1000 is an error

‘routine.

67

SECTION

FOUR -

FUNCTIONS

November 1985

0

National Instruments

rsv - Request Service/Set or Change Serial Poll

Status Byte

Serial Poll function

rsv:

Syntax:

Purpose:

Remarks:

Examples:

1 DPRINT # 1

rsv

You use rsv if the GPIB-MAC is not GPIB Controller
and you wish to request service from the Controller
using the Service Request (SRQ) signal. The GPIB-
MAC will provide a user defined status byte when the
Controller serially polls it.

The argument
decimal value of the new GPIB-MAC serial poll
response byte.

The serial poll response byte is the status byte the GPIB-
MAC provides when serially polled by another device
that is CIC. If bit 6 (hex 40 RQS bit) is also set, the
GPIB-MAC additionally requests service by asserting
the SRQ line.

If you call rsv without an argument, the GPIB-MAC
returns a numeric string containing the decimal value of
its serial poll status byte.

[ spbyte]

,“rsv \x46”

<CR>

spbyte

is a numeric string specifying the

Request service with serial poll
‘response = 6.

2, PRINT #l,“rsv”

response:

68

SECTION FOUR - FUNCTIONS

70cCRxLF>

What is the current serial poll

‘status byte?
(The current status byte=decimal

70 or hex 46)

November 1985

sic - Send Interface Clear

sic: Specialized Controller function

0

National Instruments

Syntax: sic [time]

Purpose:

You use sic if the initialization, I/O, and bus manage­ment functions do not meet the needs of your device, and

you wish more precise control over the GPIB. sic

makes the GPIB-MAC CIC and initializes the GPIB.
sic is not a function you will use frequently because in
most cases the first I/O or bus management function you
call will do this automatically.

Remarks:

The argument

number of seconds between
corresponds to time limits between 100 microseconds
and 1 hour. time must not contain a comma.

If you call sic without an argument, IFC is sent for 500
microseconds. The action of asserting IFC for at least

100 microseconds initializes the GPIB and makes the

interface board become CIC. When needed, sic is
generally used at the beginning of a program to make the
GPIB-MAC CIC and is used when a bus fault condition

is suspected.

The IFC signal resets only the GPIB interface functions
of bus devices and not the internal device functions.
Device functions are reset with the

message. To determine the effect of these messages,
consult the device documentation.

<CR>

time

is a numeric string specifying any

.OOOl

and 3600, which

clr

programming

If you are in a debugging environment, you may want to
vary the amount of time IFC is asserted. For example,
you may set time to 10 seconds to allow you to check on

a bus analyzer that IFC is actually being asserted.
Otherwise, you do not need to include the
argument.

69

SECTION FOUR - FUNCTIONS

time

November 1985

The GPIB-MAC records the ESAC error if you have
disabled its System Controller capability with the
function. It records the EARG error if you specify a
time outside the range

0

National Instruments

BOO1

to 3600.

rsc

Refer also to

Examples:

1. PRINT #l,“sic”

2. PRINT

#l,“SIC .Ol”

clr

and to Appendix D.

‘Send interface clear for 500
‘microseconds.

‘Send interface clear for 10

‘milliseconds.

70

SECTION FOUR - FUNCTIONS

0

November 1985

National Instruments

spign - Ignore Serial Port Errors

spign: Serial Port function

Syntax: spign [bool] <CR>

Purpose:

Re

narks: If the argument

You use spign at the beginning of your program if you
wish to change the effect that serial port errors have on
how the GPIB-MAC processes programming messages
and data. This function tells the GPIB-MAC to ignore or
not to ignore the occurrence of serial port errors. By
default, the GPIB-MAC ignores serial port errors.

ignore serial port errors. When
MAC does not execute programming messages that con­tain serial port errors. A list of serial port errors are
listed in Appendix B. Also, if a serial port error occurs
with any byte contained in a

GPIB-MAC discards that data byte and all remaining
bytes in the string.

The serial port errors include parity, overrun, framing,
and overflow errors.

If the argument
programming messages and sends all data, even if serial
port errors occur as the messages and data bytes are
received

No matter what value
records the errors in the serial-error portion of the status
area.

boo1

is 0, the GPIB-MAC will not

boo1

is 0, the GPIB-

cmd

or

wrt

data string, the

boo1

is 1, the GPIB-MAC executes all

boo1

has, the GPIB-MAC still

If you call spign without an argument, the GPIB-MAC
returns to you the current setting.

Refer also to

7 1

SECTION FOUR - FUNCTIONS

cmd

and

wrt.

November 1985

Examples:

0

National Instruments

1. PRINT

2.

PFUNT #l ,“spign

#l,“spign 0”

1”

‘Do not execute programming

‘messages or process data

that

‘contain serial port errors.

‘Execute all

programmh

g messages
‘and send all data, even if serial port
‘errors occur.

72

SECTION FOUR - FUNCTIONS

November 1985

sre - Set or Clear Remote Enable

sre:

Specialized Controller function

sre

Syntax:

[bool]<CR>

0

National Instruments

Purpose:

Remarks:

You use sre if the I/O and bus management functions do
not meet the needs of your device. sre gives you more
precise control over the GPIB. Use sre to turn the
Remote Enable signal on and off. sre is not a function
you will use frequently because in most cases, the first
I/O or bus management function you call will set remote
enable automatically.

If the argument
Remote Enable @EN) signal. If the argument
0, the GPIB-MAC unasserts REN.

Many GPIB devices have a remote program mode and a
local program mode. It is usually necessary to place
devices in remote mode before programming them from

the GPIB. A device enters the remote mode when the

REN line is asserted and the device receives its listen

address.

Use

cmd

sre. Use

mode.
If you call

not System Controller, the GPIB-MAC records the
ESAC error.

lot

boo1

is 1, the GPIB-MAC asserts the

boo1

is

to send a device its listen address after using

to return the device to local program

sre with

an argument and the GPIB-MAC is

If you call
returns its current remote status: l=remote,

Refer also to rsc, cmd, and

SECTION FOUR - FUNCTIONS

73

sre

without an argument, the GPIB-MAC

O=local.

lot.

November 1985

Examples:

0

National Instruments

1. PRINT

2. PRINT

#l,“SRE

#l,“sre 0”

1”

‘Set REN.

‘Unassert

REN.

74

SECTION FOUR - FUNCTIONS

November 1985

stat - Return GPIB-MAC Status

stat:

General Use function

0

National Instruments

Syntax:

Purpose:

Remarks:

stat

[[cl

n]cCR>

or

stat [c]
stat [c] n

You use

see if certain conditions are currently present. You use
stat most often to see if the previous operation resulted
in an error.

You should use stat frequently in the early stages of

your of your program development when your device’s

responses are likely to be unpredictable. The

MAC responds with status information in a form

depending on the mode or combination of modes you

chose. n indicates that the status information will be

returned as numeric strings. s indicates that the status

information will be returned in symbolic format, i.e.,

as mnemonic strings.

returned after each programming message, eliminating

the need to call

Normally, you use s only when you are debugging your

code and you want to print the mnemonic for each piece
of status information.

or

s&R>

s&R>

stat

to obtain the status of the GPIB-MAC to

c specifies that the status will be

stat

after each programming message.

GPIB-

The status information returned by the GPIB-MAC
contains four pieces of information: the GPIB-MAC
status, a gpib-error code, a serial-error code, and a
count. The GPIB-MAC returns a
each piece of the response.

75

SECTION FOUR - FUNCTIONS

<CRxLP>

following

November 1985

Status represents a combination of GPIB-MAC
conditions. Internally in the GPIB-MAC, status is
stored as a
represents a single condition. A bit value of 1 indicates
that the corresponding condition is in effect; a bit value
of zero indicates that the condition is not in effect.
more than one GPIB-MAC condition may exist at one
time, more than one bit may be set in status. The highest
order bit of status, also called the sign bit, is set when
the GPIB-MAC detects either a GPIB error or a serial
port error. Consequently, when status is negative, an
error condition exists, and when status is positive, no
error condition exists.

gpib-error represents a single GPIB error condition
present.

serial-error represents a single serial error condition
present.

count is the number of bytes transferred over the GPIB
by the last rd, wrt, or cmd function.

0

16bit

integer. Each bit in the integer

National Instruments

Since

Numeric Symbolic

Bit Value (n) Value (s) Description

15 -

32768

14
13
12

11

10
9
8
7

76

SECTION FOUR - FUNCTIONS

16384
8192

4096
2048

1024

512

256

128

GPIB STATUS CONDITIONS

ERR

TIM0

Error detected
Timeout
EOI or EOS detected

SRQI

SRQ detected while

CIC

Reserved
Reserved

Reserved

CMPL

LOK

Operation completed

Lockout state

November 1985

Bit

0

National Instruments

GPIB STATUS CONDITIONS (CONTINUED)

Numeric Symbolic

Value (n) Value (s) Description

Numeric
Value (n)

0

5

F-16

17

REM

CIC

ATN
TACS Talker active
LACS
DTAS
DCAS

GPIB ERROR CONDITIONS

Remote state
Controller-In-Charge
Attention asserted

Listener active
Device trigger state
Device clear state

Symbolic
Value (s) Description

NGER
ECIC
ENOL

EADR

EARG
ESAC

EABO

E&D

No GPIB error condition to
report
Command requires GPIB-
MAC to be CIC
Write detected no listeners

GPIB-MAC not addressed
correctly
Invalid argument or
arguments
Command requires GPIB-

MACtobeSC

I/O operation aborted
Reserved
Unrecognized command

77

SECTION FOUR - FUNCTIONS

November 1985

Numeric Symbolic

Value (n) Value (s)

0

National Instruments

SERIAL PORT ERROR CONDITIONS

Description

NSER
EPAR

EORN
EOFL

EFRM

A detailed description of the conditions under which
each bit in status is set or cleared may be found in
Appendix

In general, the GPIB-MAC updates the first three status
variables at the end of each programming message. It
updates the fourth, count, after a cmd, rd, or wrt
function The errors reported correspond to the previous
programming message. For example, if you call wrt

and then stat s, any errors returned to you correspond
to errors in the
However, if status is returned in continuous mode, the

status information corresponds to the current
programming message. For example, suppose you call

stat c s to set up continuous status reporting. After

reading the status information returned for the

you call wrt. The

information that corresponds to the wrt message.

B.

wrt

programming message, not

GPIB-MAC then returns the status

No serial port error

condition to report
Serial port parity error
Serial port overrun error
Serial port receive buffer
overflow
Serial port framing error

stat.

stat call,

Refer to the following examples for ways in which to

make use of the status information.

When you wish to begin continuous status reporting,

send the stat c s, stat c n, or stat c n s programming
message. Status information will be immediately

returned indicating the current status conditions. When

SECTION FOUR - FUNCTIONS

78

November 1985

you

always returned first.

call

stat

with both s and

0

National Instruments

n the

numeric status is

If you call stat

reporting is disabled.
Notice that when you send several programming

messages to the GPIB-MAC, it buffers them and
processes each one without any delay in between.
However, if you enable continuous status reporting and
check the status of each programming message before
sending the next, the GPIB-MAC waits for each
subsequent programming message to arrive at the serial
port before processing it. This slows down the overall
performance of your program.
concern, disable continuous status reporting.

Examples:

10

1.

PRINT

20

REM GPIB-MAC responds with:
30 REM
40

REM Now read status into variables.

50

STATUS% = VAL(LINE INPUT#l,STATUS$)

60

LINE INPUT # 1 ,GPIBERR$

70

LINE INPUT

80

LINE INPUT #l,COUNT$

90

REM Go to error routine at 500 if error occurred.

100

IP STATUS% < 0 THEN GOT0 500

110

REM Go to SRQ service routine if SRQ is asserted.

120

IF (STATUS% AND

. . .
400 REM
410 REM Place code here to service SRQ.
420 REM
500 REM Print gpib-error and serial-error values to
5 10

REM determine what errors occurred
520 PRINT “GPIB-error = “;GPIBERR$
530 PRINT “Serial-error =
540 STOP

#l,“stat n”

340<CR><LF>OcCR><LF>O<CR><LF>Oc~><LF>

without an argument, continuous status

If speed is a primary

‘Get GPIB-MAC status.

#l,SPERR$

&HlOOO) THEN

“;SPERR$

GOT0 400

SECTIONFOUR-FUNCTIONS

79

November 1985

0

National Instruments

2. 10 PRINT
20

REM If it has just read 3 bytes from the GPIB,

30

REM GPIB-MAC responds with:
40 REM
50 REM

3.

The following list illustrates what appears on the screen when
you are progr

#l,

“stat

s”

CMPL,REM,ATN,LACS<CR><LF>NGER<CR><LF>

NSER<CRxLF>3<CRxLF>

amming the GPIB-MAC from a terminal.

Programming messages you enter are in normal type. GPIB-
MAC responses are in bold. The statements in parentheses are

comments.
stat c s n

(enable continuous status reporting)

344
8

3
CMPL,REM,ATN,TACS (status returned)
NGER
NSER
3
wrt 10
ABCDE

(Write the string ABCDE)
344 (device 10.)
0

(Status returned.)

s

CMPL,REM,ATN,TACS
NGER
NSER

5

80

SECTION FOUR - FUNCTIONS

November 1985

0

National Instruments

tmo - Change or Disable Time Limit

tmo: Initialization function

Syntax:

Purpose: You use tmo at the beginning of your program to change

Remarks: The arguments timeio and timesp are numeric strings.

tmo [timeio] [ ,timesp] <CR>

the time limits in effect on the GPIB-MAC. The time

limits prevent the GPIB-MAC from hanging indefinitely

when an error situation prevents normal completion of an
operation.

timeio

GPIB-MAC waits for an I/O operation (rd, wrt, cmd)
or the wait function to complete. timesp specifies the

amount of time in seconds each device is given in which
to respond to a serial poll. The power-on timeouts are
10 seconds for timeio and

timeio and timesp may be any decimal number
between
limits between 10 microseconds and 1 hour. lO,.l
specifies a time of 10 seconds for I/O operations and

l/l0

timesp may also be 0, which disables either timeout
accordingly. Neither timeio nor timesp may contain
commas (e.g., 1000 is correct but 1,000 is not).

specifies the amount of time in seconds the

l/10

of a second for timesp.

.OOOOl

of a second for serial poll response. timeio and

and 3600 which corresponds to time

The timeio time limit is in effect for the cmd, rd,
and

wrt

functions. If the GPIB-MAC cannot complete
any of these functions within the period of time set by
timeio, it aborts the function and records the EABO
error. Bytes that were transferred before the timeout are
not affected.

The timeio

time the wait function waits when you

TIM0

81

SECTION FOUR - FUNCTIONS

time limit is also the maximum amount of

bit set in the wait mask.

caIl

it with the

November 1985

0

National Instruments

Examples:

1. PRINT

The timesp

time limit is in effect only for the

rsp

function. If a polled device fails to respond within the
amount of time indicated by

timesp, the

GPIB-MAC

returns an error flag.

Refer to the rsp programming message.
If you want to change only the timeout value for serial

polls, a comma must precede the serial poll timeout
value.

If you call tmo without an argument, the GPIB-MAC
returns a numeric string representing the

cuxmnt

timeout
settings. It records the EARG error if you specify a time
value outside the range

.OOOOl

to 3600.

The assignment made by this function remains in effect

until you call tmo again, call onl, or turn off the GPIB-

MAC.

#l,“tmo 30”

‘Set timeout for

If0

operations to 30
‘seconds; leave serial poll timeout
‘unchanged.

2.

PRINT #l,“TMO”

response:

3. PRINT

SECTION FOUR - FUNCTIONS

82

30,.1cCR>eLF>

#l,“tmo ,l”

‘Print current timeout settings.

‘Set serial poll timeout for one second;
‘leave

If0

timeout unchanged.

November 1985

0

National Instruments

- Trigger Selected Device(s)

trg

Bus Management function

trg :

Syntax:

Purpose:

Remarks:

trg

alis t&R>

You use
instructions for each GPIB device explain when you
should trigger them and what effect the trigger has.

The argument
by commas or spaces. addrs are device addresses that
specify the GPIB addresses you wish to trigger.

A device address consists of a primary address and an
optional secondary address. The secondary address is
separated from the primary address by a plus sign

Only the lower five bits of each address are significant.
These bits may be in the range from 0 through 30 for

both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

trg

to trigger the specified devices. The

alist

is a list of addrs separated

*

(+).

If you call
posted.

If this is the
controller capability, and you have not disabled System
Controller capabiltity with
Interface Clear
Remote Enable.

83

SECTION FOUR - FUNCTIONS

trg

0+2

or

0+98

or

32+98

or

O+\x62

without an argument, the EARG error is

fust

function you call that requires GPIB

rsc, the

(IX)

to make itself CIC. It also asserts

GPIB-MAC sends

November 1985

0

National Instruments

If you passed control to some other GPIB
must be passed back to you or you must send IFC to
make yourself CIC before making this call. Otherwise,
the ECIC error will be posted.

Example:

PRINT

#l,“trg 2+10,4,5+7”

* frequently used function

device,control

‘Trigger 3 devices.

SECTION FOUR - FUNCTIONS

84

November 1985

wait - Wait for Selected Event

wait: General Use function

Syntax: wait mask<CR>

0

National Instruments

Purpose: You use

wait

delay any further GPIB-MAC activity until one of them

occurs.

Remarks: The argument

the events to wait for. The numeric string represents a
bit mask containing a subset of the same bit assignments
as the status word described in the stat function. Each
bit is set or cleared to wait or not to wait, respectively,
for the corresponding event to occur. The numeric string
may be expressed as decimal, octal, or hexadecimal.

After receiving the
GPIB-MAC monitors GPIB activity. When any event
corresponding to the bits set in

MAC

returns status information indicating its current
status. If continuous status reporting has been enabled,
status will be reported in the format requested. If

continuous status has not been enabled, status will be
returned in numeric format.

You could use wait, for example, if you wish to wait
until a device requests service before you perform a
serial poll. In this case you send the wait programming
message with
information to be returned. You then check that status to
see if the SRQI bit is set in the returned status indicators.

to monitor selected GPIB events and to

mask

is a numeric string which specifies

wait

programming message, the

mask=4096,

mask occurs, the

then wait for status

GPIB-

To

prevent the GPIB-MAC from waiting indefinitely for

SRQ to be asserted, set the SRQI and
setting the mask equal to 4096 + 16384. This will
cause the wait to terminate either on SRQI or TIMO,
whichever occurs first.

85

SECTION FOUR - FUNCTIONS

TIM0

bits by

November 1985

0

National Instruments

It is recommended that you always include the

value in mask when you wait for an event.

WAIT MASK VALUES

Hex Decimal

Bit Value Value

15
14
13
12

11
10

9

8

7

5”

4

;
:

4000

1000

80-

40

20

10

:

2

1

16384

4096

128
64

32

16

:

2

1

Mne-

manic Description

Reserved

T&O

SRQI

LOK
REM

CIC

ATN
TACS
LACS
DTAS
DCAS

Timeout
Reserved

SRQ detected while

CIC

Reserved
Reserved

Reserved
Reserved
Lockout state
Remote state
Controller-In-Charge

Attention asserted

Talker active
Listener active

Device trigger state

Device clear state

TIM0

bit

If mask=0 the function completes immediately,
If the

TIM0

with tmo, timeouts for this function are disabled. You
should disable timeouts only when you are certain the
selected event will occur; otherwise, the GPIB-MAC
waits indefinitely for the event to occur.

If you call
records the

Refer also to

SECTION FOUR - FUNCTIONS

86

wait

bit is 0 or the

without an argument, the GPIB-MAC

EARG

stat

error.

and

timeio time

tmo.

limit

is set to 0

November 1985

0

National Instruments

Examples:

1.

PRINT

#l,“wait \x5000”

‘Wait for

TIM0

or SRQI.
STATUS%=VAL(LINE INPUT #l,STATUS$)‘Get status info.

GPIBERR%=VAL(LINE IN-PUT # 1 ,GPIBERR$)
SPERR%=VAL(LINE INPUT #l,SPERR$)
COUNT%=VAL(LINE INPUT #l,COUNT$)

IF (STATUS% AND

&H4000) <>

‘If

TIM0

0 THEN GOT0 1000

bit is set we timed out before
‘getting SRQI. Go to an error routine
‘at line 1000.

IF(STATUS% AND

&HlOOO) <>

0 THEN GOT0 200
‘If SRQI bit set, go to routine to
‘conduct a serial poll.

2. PRINT

#l,“wait 4”

‘Wait indefinitely to become LACS.

STATUS%=VAL(LINE INPUT #l,STATUS$)‘Get status info.
GPIBERR%=VAL(LINE

INPUT #l ,GPIBERR$)
SPERR%=VAL(LINE INPUT #l,SPERR$)

COUNT%=VAL(LINE INPUT #l,COUNT$)

PRINT

#l,“rd lo” ‘Now that GPIB-MAC is addressed to

‘listen, read 10 bytes from the GPIB.

RESP$=INPUT$(

lO,#l)

‘Input 10 bytes from serial port

‘buffer.

LINE INPUT # 1 ,CNT!§

‘Input number of valid bytes in CNT$.

87

SECTION FOUR - FUNCTIONS

November 1985

0

National Instruments

wrt - Write Data

I/O function

W-l-t:

wrt

Syntax:

Purpose:

Remarks:

[#count][alist]<CR>

data&R>

You use
The argument count is a numeric string preceded by a

number sign

1 and 65535 and must not contain a comma. #count

specifies the number of data bytes to send. The number
of data bytes must not include the carriage return that
indicates the end of the programming message.

The argument

are transferred without any translation to the GPIB.

The argument

commas or spaces.

GPIB

than one address is given).

A device address consists of a primary address and an

optional secondary address. The secondary address is
separated from the primary address by a plus sign

wrt

addresses of the Listener (or Listeners, if more

*

to send data over the GPIB.

(#).

The string specifies a number between

data

is a string of 8-bit characters which

alist

is a list of addrs separated by

addrs are

addresses that specify the

(+).

Only the lower five bits of each address are significant.
These bits may be in the range from 0 through 30 for
both the primary and the secondary address. Therefore,
the binary value 01100010 (decimal 98) is interpreted as
decimal 2.

The following examples all specify a primary address of
0 and a secondary address of 2. The listen address is
32, the talk address is 64, and the secondary address is 2
or 98, which are equivalent.

0+2

SECTION FOUR - FUNCTIONS

88

or

0+98

or

32+98

or

O+\x62

November 1985

When #count is not specified, the GPIB-MAC
recognizes the end of the data string when it sees a
carriage return or a line feed. #count is required when
your data string contains embedded carriage return or

linefeed characters.

If you specify an address list, the GPIB-MAC must be
CIC to perform the addressing. If this is the first
function you call that requires GPIB controller
capability, and you have not disabled System Controller
capability with rsc, the GPIB-MAC sends Interface
Clear (IFC) to make itself CIC.

If you passed control to some other GPIB device,
control must be passed back to you or you must send

IPC to make yourself CIC before making this call.

Otherwise, the ECIC error will be posted.

0

National Instruments

If you do not give an
CIC, it assumes it will be addressed by the controller. If
you do not give an alist and the GPIB-MAC is CIC, it
addresses itself as talker and assumes the listeners are
already addressed.

The first part of this programming message, up to

<CR>, is buffered, meaning the GPIB-MAC will not act
upon it until it receives <CR>. The string that follows
the first line is piped to the

allows you to send a string larger than the

internal buffer with one programming message.

The GPIB-MAC aborts the GPIB write if it receives
Device Clear or Selected Device Clear and its Listen

Address. The GPIB-MAC aborts the

records the EABO error if, at any time during the GPIB

write, the time limit set for I/O functions expires. This

89

SECTION FOUR - FUNCTIONS

alist

and the GPIB-MAC is not

GPIB,

non-buffered. This

GPIB

GPIB-MAC’s

write and