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Model
DRC-93C
Section IV
4 . 4 . 3
The
IEEE-488
INTERFACE bus
All
devices equipped to implement
address for the DRC-93C is set by
such commands will do so simul-
switches
4
through
8
which are
taneously when
the
command
is
reserved for the address selection.
transmitted.
As
with all multiline
Switch
4
is the most significant bit
commands, these commands are trans-
(MSB[=16]) and
8
is the least sig-
mitted
with
ATN
line
asserted
nificant bit (LSB[=1]).
(low).
There are two Universal
commands recognized by the DRC-93C,
The factory preset address of this
Local Lockout and Device Clear.
instrument is 12 (see Table
4-2).
Address switch numbers
5
and
6
LLQ
(Local Lockout)
-
LLQ
is sent to
should be CLOSED
(1)
which will
instruments to lock out (prevent the
result in the Address Switch having
use of) their front panel controls.
a setting of
00001100
or
10001100
dependent on the requirements for
DCL (Device CLear)
-
DCL is used to
the delimiters.
return the DRC-93C to the power-up
conditions.
4 . 5 . 3
The
Addressed commands
4 . 5 . 1
The Uniline
Command
The Addressed Commands shown in
A Uniline Command (Message) is a
Table
4-3
are multiline commands
command which results in a single
that must
include the
DRC-93C
signal line being asserted.
The
listen
address before
it will
DRC-93C recognizes two of these
respond to the command in question.
messages from the BUS
CONTROLLER,
Note that only the addressed device
REN and IFC (See Table
4-3).
When
will respond to these commands.
the
B U S
CONTROLLER
executes the ap-
The DRC-93C recognizes three of the
propriate software code the effect
Addressed commands;
SDC
(Selective
is to pull the corresponding Inter-
Device Clear), GTL (Go To Local),
face Management line low.
For
and SPE (Serial Poll Enable).
example, when the software command
REMOTE712 is executed by the HP86
SDC
(Selective Device Clear)
-
The
digital computer, the management
SDC
command performs essentially
line
REN
is pulled low and the listen
the same function as the DCL command
address
12
issued to signal the
except that only the addressed
instrument having address
12
(DRC-
device responds. Generally,
instruments
93C) to go into the remote mode.
return to their power-up default
conditions when responding to the
The SRQ is a uniline command asserted
SDC
command.
by the DRC-93C when it wishes to
signal the BUS CONTROLLER. The
B U S
GTL (Go To Local)
-
The GTL command
CONTROLLER
will in turn use the
is used to remove instruments from
Addressed command SPE (Serial Poll
the remote mode. With some instru-
Enable) described below to inter-
ments, GTL also unlocks front panel
rogate the DRC-93C about the reason
controls if they were previously
or reasons for the communication.
locked out with the LLO command.
4 . 5 . 2
The Universal
Commands
SPE (Serial Poll Enable), SPD (Serial
Poll Disable) -Serial polling is used
The Universal Commands shown in
to obtain the SRQ Status Register.
Table
4-3
are those multiline
The Status Register contains
important
commands that address all devices
operational information from the
on the bus.
A multiline command
unit requesting service.
The SPD
involves a group of signal lines.
command ends the polling sequence.
4 . 5 IEEE-488 BUS
COMMANDS
COPYRIGHT 3/88
LSCI
4-5
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