There is a driver available for that instrument from Thurlby Thrandar. According to the information from NI's link, the driver supports RS-232, GPIB, and USB interfaces. You will need to check to see what type of programming interface is on your instrument. If it's only GPIB, you will need to purchase a GPIB controller for your pc. Since the driver is IVI, you will also need to install the IVI compliance package. You can install that from your LabVIEW Drivers CD or get the latest here. You should get started with the large amount of information on the Instrument Driver Network. You will find links to instrument control tutorials, explanation of what an instrument driver is and how to use one, etc. As long as you have the programming manual for the instrument, you could also try the Instrument I/O Assistant.
