Hi,
To communicate with GPIB you need a GPIB interface and the driver. If you are using a NI GPIB interface, you need the NI-488.2 driver.
The driver provides you with the functionality to send and receive messages throught the GPIB bus. The GPIB is only the communication channel. What you send or receive depends on the device you are using.
The driver comes with some generic examples (there are examples for VC++). This examples show you the functions necessary to send and receive data to a device on the bus. Most examples will use the *IDN? command, which is a data command defined in the IEEE 488.2 standard. Most instruments will respond to this query with an idetification string. You can use this examples to get a feel on how to send and rece
ive data.
To control your instrument you need the programmer's (or user's) manual. The manual will give you all the commands accepted by the instrument and the format of the data returned by the instruments. Most of the times, instrument manuals will include examples on how to perform simple operations on the device. The language used in the examples is not important (it might be pseudo-code), what you are interested in is the string commands (messages) sent to the instrument and the way the data returned is parsed.
Hope this helps.
DiegoF.
National Instruments