Agilent Technologies HP 82335, Инструкция по установке, Страница: 45 / 54

HP-18 Fundamentals
Bus Commands
Addressed Commands
Addressed commands are executed only by those devices that are currently
addressed
as
listeners. They allow the controller to initiate a simultaneous
action by a selected group of devices on the bus, such as triggering them to
take readings at the same time. The commands are listed in Table A-2.
Mnemonic Command
Table A-2. Addressed Commands
Description
SDC Selected Device Clear Similar
10
a Universal Device Clear (DCl)
with
only those devices
addressed to listen responding.
GTL
Go To Local
GET Group Execute Trigger
PPC Parallel Poll Configure
TCT
Take Control
Returns devices that are addressed to listen to Local mode (re­
enables front panel pr
o
g
r
a
mm
ing)
.
REN stays asserted when
a
GTl is sent, and devices will be relumed
10
Remote upon receipt
of their listen address.
Initiaies some preprogrammed action by lis t e n i
n
g devices. This
may be used to simultaneously start action in a group of devices
that are addressed to listen.
Configures a device to respond
to
a parallel poll on a specified
data line with either
a
positive or negative si
g
nal.
A
secondary
command sent after PPG contains the data that configures the
device.
Transfers active controller status to another device on the bus.
(This command is executed by the current talker, not the current
set of listeners.)
Unaddress Commands
The two unaddress commands can be considered as extensions of talk and
listen addresses
.
• UNL (Unlisten) causes all devices on the bus (except those that have a
built-in
switch set to Listen Only) to stop being listeners. UNL is
equivalent to listen address 3 1 .
• UNT (Untalk) directs any device on the interface to no longer be
addressed as talker. Since there may only be one device addressed to talk
at any time, receipt of another device's talk address is equivalent
to
receiving a UNT. UNT is equivalent
to
talk address 3 1 .
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A