Are you trying to use the USB ports on a Real-Time PXI controller? Or are you running in Windows? I suspect you are using the USB ports on a Windows-based PC. If that is the case, please search for your question in the LabVIEW General group. I know it has been asked before. If you don't find an adequate answer there, you might try posting the question again in that group.
In general, LabVIEW can talk to a DLL that interfaces to 3rd party hardware. That driver (typically a DLL) would be supplied by the hardware manufacturer.
