Hello,
There is a very good reference on the functions that you can call for GPIB in C or C++. Once you have installed the 488.2 driver, if you go to Windows»Start»Programs»National Instruments» NI-488.2 »NI-488.2 Help.
It will contain all the functions that you can use.
Here I attached a C code for LabWindows/CVI which contains also some functions for a front panel. The important thing is to see how you use the ibdev, or ibwrt or ibrd commands.
Basically what you need is the functions I just mentioned.
You can find more examples in the Developer Zone. Look for CVI examples for GPIB and will be matter of just reading the C code.
Best Regards,
Ricardo Santa Olalla
National Instruments.