# Selecting RS232C or RS-485/RS-422

Please refer to the Catalyst Operator’s Manual section 2.5 – Catalyst RTU Interior View Diagram. Find the location of the jumper field P10. Shown below is the configuration of jumper shunts for both RS-232C and RS-485/422. Each rectangle around two numbered pins represents a jumper shunt.

RS-232 Configuration (Default) | RS-485 or RS-422 Configuration

If the Catalyst is NOT at either endpoint of the RS-485/RS-422 network then the termination resistor jumper (Pins 17 &18) should be set as shown below:

RS-485/RS4-422 Configuration w/o Termination Resistor