USB communication is supported with NI-VISA 3.0 and later on Windows and with NI-VISA 3.2 and later on Macintosh and Linux. NI-VISA supports instrument class 488.2 devices conformant to the USBTMC spec and non-class devices that do not have a default Windows driver. For more information on controlling a USB device with NI-VISA, please review the Developer Zone tutorial "Using NI-VISA 3.2 to Control Your USB Device" linked below.
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/42b604435e3f9604862565e20043cd30?OpenDocument