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Chapter 1
NI-488.2M Software Description
The remainder of this chapter discusses the basics of GPIB and how to set up
your system. For application program examples, refer to Chapter 2, Application
Examples. For information about writing an application program, refer to
Chapter 3, Developing Your Application.
GPIB Overview
The following sections describe the elements of a GPIB system.
The IEEE 488 Standard and GPIB
The ANSI/IEEE Standard 488.1-1987, IEEE Standard Digital Interface for
Programmable Instrumentation, describes a standard interface for
communication between instruments and controllers from various vendors. It
contains information about electrical, mechanical, and functional specifications.
The ANSI/IEEE Standard 488.2-1987, Codes, Formats, Protocols, and
Common Commands, defines a bus communication protocol, a common set of
data codes and formats, and a generic set of common device commands.
The GPIB (General Purpose Interface Bus) is a digital, 8-bit parallel
communications interface with data transfer rates of 1 Mbytes/s and above. The
bus supports one System Controller, usually a computer, and up to 14 additional
instruments.
Talkers, Listeners, and Controllers
Devices on the GPIB can be Talkers, Listeners, or Controllers. A Talker sends
out data messages. Listeners receive data messages. The Controller, usually a
computer, manages the flow of information on the bus. It defines the
communication links and sends GPIB commands to devices.
Some devices are capable of playing more than one role. A digital voltmeter,
for example, can be a Talker and a Listener. If your personal computer has a
GPIB interface board and GPIB software installed, it can function as a Talker,
Listener, and Controller.
© National Instruments Corp.
1-5
NI-488.2M SRM for OS/2
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