Since all your existing equipment is GPIB, you may be overlooking something very basic. If this is aimed too low, I apologize. I don't know what your level of experience is, and if I underestimate your capability here, please don't take offense. I assume you have selected your relays (or at least have the connections figured out) already, but you haven't figured out a way to drive them with LabVIEW.
You will need an additional DAQ card or module with Digital Outputs to drive them.
The simple solution is to get a general purpose DAQ card and add it to your setup. Choose something with Digital I/O, and depending on how much current it takes to energize your selected relays, you might be able to energize the relays directly with the Digital Output. If not, you will need to add a simple transistor drive circuit (controlled by the Digital Output) to energize the relays. If you need suggestions for the DAQ hardware, NI offers alot of DAQ equipment with Digital I/O capability. USB DAQ hardware is easy to use, and is probably the cheapest way to go. The NI-USB-6501 is only $99.00. Good luck.
