Keithley 617 User Manual

SECTION 3
IEEE-488 PROGRAMMING
3.1 INTRODUCTION
The IEEE-488 bus is an instrumentation data bus with hard-
ware and programming standards originally adopted by the
IEEE (Institute of Electrical and Electronic Engineers) in 1975
and given the IEEE488 designation. In 1978, standards were
upgraded into the IEEE-488-1978 standards. The Model 617
conforms to these IEEE-488.1978 standards.
This section contains general bus information as well as the
necessary programming information and is divided into the
following sections:
1. Introductory information pertaining to the IEEE-488 bus in
general is located in paragraphs 3.2 through 3.6.
2. Information necessary to connect the Model 617 to the
IEEE-486 bus is contained in paragraphs 3.7 and 3.8.
3. General bus command programming is covered in para-
graph 3.9.
4. Devicedependent command programming is described in
paragraph 3.10. These are the most important commands
associated with the Model 617 as they control most of the
instrument functions.
5. Additional information necessary to use the Model 617
over the IEEE-488 bus is located in the remaining para-
graphs.
3.2 BUS DESCRIPTION
The IEEE-488 bus, which is also frequently referred to as the
GPIB (General Purpose Interface Bus), was designed as a
parallel transfer medium to optimize data transfer without us-
ing an excessive number of bus lines. In keeping with this
goal, the bus has only eight data lines that are used for both
data and with most commands. Five bus management lines
and three handshake lines round out the complement of bus
signal lines.
A typical configuration for controlled operation is shown in
Figure 3-l. The typical system will have at least one controller
and one or more devices to which commands are given and,
in most cases, from which data is received. Generally, there
are three categories that describe device operation: controller,
talker, and listener.
Figure 3-1. IEEE Bus Configuration
The controller does what its name implies: it controls other
devices on the bus. A talker sends data (usually to the con-
troller), while a listener receives data. Depending on the in-
strument, a particular device may be a talker only, a listener
only, or both a talker and a listener.
3-l

Keithley 617 Specifications

General

Brand	Keithley
Model	617
Category	Measuring Instruments
Language	English