Agilent Technologies 11896A, User'S And Service Manual

Page: 82 / 140

Programming
Programming over GPIB
Communicating over the bus
(HP 9000 series 200/300 controller)
Since GPIB can address multiple devices through the same interface card, the
device address passed with the program message must include not only the
correct interface select code , but also the correct instrument address .
Interface select code
(selects interface)
Each interface card has a unique interface select code . This code is used
by the controller to direct commands and communications to the proper
interface . The default is typically \7" for GPIB controllers .
Instrument address
(selects instrument)
Each instrument on a GPIB must have a unique instrument address between
decimal 0 and 30. The device address passed with the program message must
include not only the correct instrument address , but also the correct interface
select code .
DEVICE ADDRESS = (Interface Select Code * 100) + (Instrument
Address)
F or example , if the instrument address for the polarization controller is 4
and the interface select code is 7, when the program message is passed, the
routine performs its function on the instrument at device address 704.
F or the polarization controller , the instrument address is typically set to \20"
at the factory . This address can be changed in the GPIB menu.
N O T E
The examples in this manual assume the polarization controller is at device address 720.
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