Application Examples
Chapter 2
NI-488.2M UM for Windows NT
2-14
© National Instruments Corp.
Example 6: Basic Communication with
IEEE 488.2-Compliant Devices
This example provides an introduction to communicating with IEEE 488.2-compliant
devices.
A test engineer in a metal factory is using IEEE 488.2-compliant tensile testers to find out
the strength of metal rods as they come out of production. There are several tensile
testers and they are all connected to a central computer equipped with an IEEE 488.2
interface board. These machines are fairly voluminous and it is difficult for the engineer
to reach the address switches of each machine. For the purposes of his future work with
these tensile testers, he needs to determine what GPIB addresses they have been set to.
He can do so with the aid of a simple application he has written. The following steps
correspond to the program flowchart in Figure 2-6.
1.
The application initializes the GPIB by bringing the interface board in the computer
online.
2.
The application issues a command to detect the presence of listening devices on the
GPIB and compiles a list of the addresses of all such devices.
3.
The application sends an identification query (
“*IDN?”
) all of the devices detected
on the GPIB in Step 2.
4.
The application reads the identification information returned by each of the devices
as it responds to the query in Step 3.
5.
As a cleanup step before exiting, the application returns the interface board to its
original state by taking it offline.
