Agilent Technologies HP 82335, Install Manual, Page: 44 / 54

HP-IS
Fundamentals
Bus Commands
Bus Commands
Five types of information are transmitted when the bus is
o
p
era
t
ing in
Command mode (that is, when ATN is asserted):
•
Talk addresses
• Listen addresses
• Universal commands
•
Addressed commands
• Unaddress commands
Talk addresses and listen addresses were discussed earlier in this appendix.
The other categories are described in the following subsections.
Universal Commands
Universal
commands are
r
ec
e
iv
e
d by
all
responding devices
on
the bus
whether addressed to listen or not. The commands are listed in Table A-I..
Table A-l. Universal Commands
Mnemonic
Command
LLO Local lockout
DCl
Universal Device Clear
PPU Parallel Poll Unconfigure
SPE Serial Poll Enable
SPD Serial Poll Disable
A
Description
Disables the front panel of the responding device. The REN line
must be asserted in order for lLO to have any effect. If the
instrument is already in Remote mode, the lockout will be
immediate. Otherwise, the lockout will commence when the device
receives its listen address.
All
devices capable ot responding are returned to some known,
device-dependent state. In some cases, a device will perform a
self-test
in
response to a Universal Device Clear.
Directs all devices on the HP-IS that have parallel poll configure
capabilities to not respond to a parallel poll.
Enables Serial Poll mode on Ihe interface.
Disables Serial Poll mode on the interface.
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