Hp-Ib Bus Addressing - HP 16500C Programmer's Manual

Programming Over HP-IB

HP-IB Bus Addressing

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An instrument, therefore, may be talk-addressed, listen-addressed, or
unaddressed by the controller.
If the controller addresses the instrument to talk, it will remain configured to
talk until it receives:
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an interface clear message (IFC)
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another instrument's talk address (OTA)
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its own listen address (MLA)
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a universal untalk (UNT) command.
If the controller addresses the instrument to listen, it will remain configured
to listen until it receives:
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an interface clear message (IFC)
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its own talk address (MTA)
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a universal unlisten (UNL) command.
HP-IB Bus Addressing
Because 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 the 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 the Instrument)
Each instrument on the HP-IB port must have a unique instrument address
between decimals 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.
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