Ieee-488 Interface; Description; Signal Identification; Codes And Addresses - IET Labs, Inc. RLC Digibridge 1693 User And Service Manual

1693 RLC Digibridge

2.7 IEEE-488 Interface

2.7.1 Description

If you have the IEEE Interface option 1689-9640 (see
Figure 2-2), you can use this instrument as part of a
system comprised of other test instruments, printers
and a PC, with each assigned its own bus address. The
simplest system could consist of this instrument and
just a printer. The documentation of each instrument
describes the details of how to communicate with it,
and how it communicates with other instruments, as
appropriate.

Figure 2-2: IEEE-488 interface

All instruments are inter-connected using standard
IEEE-488 cables, in nearly any combination of hub
and daisy-chain connections, subject only to length-
of-run restrictions. Standard IEEE-488 connectivity
uses a 24-pin connector carrying 16 signal lines plus
several ground connections and a shield.
This instrument will function as either TALK/
LISTEN or a TALK ONLY device in the system, de-
pending on the position of the TALK switch. "TALK/
LISTEN" denotes full programmability and is suited
for use in a system that has a controller or computer
to manage the data flow. The "handshake" routine as-
sures that the active talker proceeds slowly enough for
the slowest listener that is active, but not limited by
any inactive (unaddressed) listener. "TALK" is suited
to a simpler system -- e.g. Digibridge and printer --
with no controller and no other talker. Either mode
provides measurement results to the active listeners
in the system.

2.7.2 Signal Identification

For a key to signal names, functions, and pin num-
bers. Further explanation is found in the IEEE-488.2
Standard.
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2.7.3 Codes and addresses

General. The device-dependent messages, such as in-
strument programming commands and measurement
data (which the digital interface exists to facilitate),
have to be coded in a way that is compatible between
talkers and listeners . They have to use the same
language. Addresses have to be assigned, except in
the case of a single "talker only" with one or more
"listeners" always listening. The Standard sets ground
rules for these codes and addresses.
In this instrument, codes for input and output data
have been chosen in accordance with the IEEE-488.2
rules . The address (for both talker and listener func-
tions) is user selectable, as explained below.
Instrument Program Commands. The set of com-
mands used in remote programming is an input
data code to which the instrument will respond as a
"talker/listener", after being set to a remote code and
addressed to listen to device-dependent command
strings. The set includes all of the keyboard func-
tions except switching external bias ON/OFF and full
recalibration, which are not remotely programmable.
Refer to paragraph 3.11.7 for a table of the commands
used in programming.
Address. The initial setting of address,, provided by
the factory, is binary 00011, decimal 3. Consequently,
the talk address command (MTA) is C in ASCII code
and, similarly, the listen-address command (MIA) is
#. If a different address pair is desired, set it manually
using the following procedure.
Installation