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Chapter 4 Developing Your NI-488.2 Application
NI-488.2 User Manual 4-10 ni.com
Initialization
Step 1. Become Controller-In-Charge (CIC)
Use
SendIFC to initialize the bus and the GPIB interface so that the GPIB
interface is Controller-In-Charge (CIC). The only argument of
SendIFC is
the GPIB interface number, typically 0 for
GPIB0.
Step 2. Determine the GPIB Address of Your Device
Use
FindLstn to find all the devices attached to the GPIB. The FindLstn
function requires the following parameters:
• Interface number (typically 0, for
GPIB0).
• A list of primary addresses, terminated with the
NOADDR constant.
• A list for reported GPIB addresses of devices found listening
on the GPIB.
• Limit, which is the number of the GPIB addresses to report.
Use
FindLstn to test for the presence of all of the primary addresses that
are passed to it. If a device is present at a particular primary address, then
the primary address is stored in the GPIB addresses list. Otherwise, all
secondary addresses of the given primary address are tested, and the GPIB
address of any devices found is stored in the GPIB addresses list. When you
have the list of GPIB addresses, you can determine which one corresponds
to your instrument and use it for subsequent calls.
Alternately, if you already know your GPIB device’s primary and
secondary address, you can create an appropriate GPIB address to use in
subsequent NI-488.2 calls, as follows: a GPIB address is a 16-bit value that
contains the primary address in the low byte and the secondary address in
the high byte. If you are not using secondary addressing, the secondary
address is 0. For example, if the primary address is 1, then the 16-bit value
is 0x01; otherwise, if the primary address is 1 and the secondary address is
0x67, then the 16-bit value is 0x6701.
Step 3. Initialize the Devices
Use
DevClearList to clear the devices on the GPIB. The first argument
is the GPIB interface number. The second argument is the list of GPIB
addresses that were found to be listening as determined in Step 2.