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Chapter 4 Developing Your NI-488.2 Application
NI-488.2 User Manual 4-8 ni.com
General Program Steps and Examples
The following steps show you how to use the traditional NI-488.2
device-level calls in your application. The NI-488.2 software includes the
devquery source code example to demonstrate these principles.
Initialization
Step 1. Open a Device
Use
ibdev to open a device handle. The ibdev function requires the
following parameters:
• Connect board index (typically 0, for
GPIB0).
• Primary address for the GPIB instrument (refer to the instrument user
manual or use the
FindLstn function to dynamically determine the
GPIB address of your GPIB device, as described in Step 2. Determine
the GPIB Address of Your Device in the Applications That Use
Multiple Interfaces or Communicate with Multiple GPIB Devices
section later in this chapter).
• Secondary address for the GPIB instrument (0 if the GPIB instrument
does not use secondary addressing).
• Timeout period (typically set to T10s, which is 10 seconds).
• End-of-transfer mode (typically set to 1 so that EOI is asserted with the
last byte of writes).
• EOS detection mode (typically 0 if the GPIB instrument does not use
EOS characters).
A successful
ibdev call returns a device handle, ud, that is used for all
device-level traditional NI-488.2 calls that communicate with the GPIB
instrument.
Step 2. Clear the Device
Use
ibclr to clear the device. This resets the device’s internal functions to
the default state.
Device Communication
Step 3. Communicate with the Device
Communicate with the device by sending it the
"*IDN?" query and then
reading back the response. Many devices respond to this query by returning
a description of the device. Refer to the documentation that came with your
GPIB device to see specific instructions on the proper way to communicate
with it.