Ieee-488 Interface Overview - Fluke 525A User Manual

525A
Users Manual

IEEE-488 Interface Overview

The IEEE-488 parallel interface sends commands as data and receives
measurements and messages as data. The maximum data exchange rate is 1 Mbyte,
with a maximum distance of 20 meters for the sum length of the connecting cables.
A single cable should not exceed 4 meters in length. Some commands are reserved
for RS-232 serial operation because these functions must be implemented as IEEE
messages per the IEEE Standards. For example, the command REMOTE could be
sent as data over the IEEE-488 interface to place the Calibrator into remote, but it
is not because the IEEE Standards call for the remote function to be sent to the
device as the uniline message REN. This is also true for several other commands
and functions, as shown below, with their equivalent RS-232 emulation. A
summary of IEEE-488 messages is shown in Table 4-3.
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4-10
Table 4-3. RS-232 Emulation of IEEE-488 Messages
IEEE-488 Message
GTL
GTR
LLO
SDC, DCL
GET
SPE, SPD
UNL, UNT
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RS-232 Equivalent
LOCAL command
REMOTE command
LOCKOUT command
(not emulated on RS-232)
(not emulated on RS-232)
(not emulated on RS-232)
(not emulated on RS-232)