General program steps and examples, General program steps and examples -8 – National Instruments NI-488.2 User Manual

Page 45

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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.

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