RS485 is simply a physical-layer protocol defining pinouts, signal levels and the like. To make the connection you need either an RS232-RS485 converter (check with BlackBox) or an RS485 serial IO card (check with NI). Either way, there should be no changes required to you Modbus drivers or other software.
Mike...
Certified Professional Instructor Certified LabVIEW Architect LabVIEW Champion
You may need to set the transceiver mode of the IO card - which is done either in the control panel or via an IOCTL/VISA call (depending on the manf of the card).
