Communicating Over The Hp-Ib Bus (Hp 9000 Series 200/3Oo Controller) - HP 1650B Programming Reference Manual

Communicating
Over the HP-IB
(HP 9000
Bus
Series 200/300
Controller)
HP 1650B/HP 16518
Programming Reference
Since HP-IB can address multiple devices through the same interface
card, the device address passed with the program message must include
not only the correct instrument address, but also the correct interface
code.
Interface Select Code (Selects Interface). Each interface card has its own
interface select code. This code is used by the controller to direct
commands and communications to the proper interface. The default is
always "7" for HP-IB controllers.
Instrument Address (Selects Instrument). Each instrument on the
HP-IB port 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) X 100 + (Instrument Address)
For example, if the instrument address for the HP 1650B/51B 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.
Programming Over HP-IB
2-3