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Interface select
code (selects
interface)
Instrument
address (selects
instrument)
Lockout
Bus commands
Each interface card has a unique interface select code. This code is used by
the controller to direct commands and communications to the proper inter-
face. The default is typically "7" for GPIB controllers.
Each instrument on an 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)
For example, if the instrument address for the instrument 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.
For this instrument, the address is typically set to "11" at the factory. This
address can be changed by pressing the LOCAL key on the front panel.
NOTE
The examples in this manual assume the instrument is at device address 711.
With GPIB, the instrument is placed in the lockout mode by sending the local
lockout command (LLO). The instrument can be returned to local by sending
the go-to-local command (GTL) to the instrument.
NOTE
Cycling the power also restores front panel control.
The following commands are IEEE 488.1 bus commands (ATN true). IEEE
488.2 defines many of the actions which are taken when these commands are
received by the instrument.
The device clear (DCL) or selected device clear (SDC) commands clear the
input and output buffers, reset the parser, and clear any pending commands.
The interface clear (IFC) command halts all bus activity. This includes unad-
dressing all listeners and the talker, disabling serial poll on all devices, and
returning control to the system controller.
Programming
Programming over GPIB
4-7
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