Communication Gateway - What pins are what on the RS485 (Modbus) Terminal Block? (eg. Rx+, Rx-, Tx+ and correct orientation)
Pin 1 - 15V input Pin 2 - Ground Pin 3 - RS485 A Pin 4 - RS485 B RS485 is a bidirectional differential bus so there is no transmit and receive. Pin 1 is on the right when looking at the connector. See attached diagram.