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Programming via GPIB and VXI
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Agilent VISA User’s Guide 81
message-based device interprets the SCPI command. In this case you
can use the VISA formatted I/O or non-formatted I/O functions and
program the message-based device as you would a GPIB device.
However, if the message-based device has shared memory, you can
access the device's shared memory by doing register peeks and pokes.
VISA provides two different methods you can use to program directly to
the registers: high-level memory functions or low-level memory
functions.
A register-based VXI device typically does not have a processor to
interpret high-level commands. Therefore, the device must be
programmed with register peeks and pokes directly to the device's
registers. VISA provides two different methods you can use to program
register-based devices: high-level memory functions or low-level
memory functions.
GPIB Interfaces Overview
As shown in the following figure, a typical GPIB interface consists of a
Windows PC with one or more GPIB cards (PCI and/or ISA) cards
installed in the PC, and one or more GPIB instruments connected to the
GPIB cards via GPIB cable. I/O communication between the PC and the
instruments is via the GPIB cards and the GPIB cable. The following
figure shows GPIB instruments at addresses 3 and 5.