User`s manual

Hardware Installation
Smartio C168H/PCI User’s Manual 2-5
RS-422 Mode
Set the DIP switch to the OFF position to use the RS-422 interface. This means that
the port is set to full-duplex; i.e., it is always ready to simultaneously transmit and
receive data.
RS-485 Mode
Set the DIP switch to the ON position to use 2-wire RS-485 communication. This
means that the port is set to half-duplex; i.e., it can transmit data only when RTS is
asserted, and can receive data only when RTS is not asserted.
Refer to the chapter Connection Option (Opt8x) and Cable Wiring for RS-422/485
cable wiring specs, and to the chapter Serial Programming Tools for Opt8J RS-485
programming details.