Specifications

Autopatch 1YDM 4YDM Serial Connections:
Pin 1 -- open for RS232, grounded for RS422/485
Pin 2 -- RS232 RxData (receives from IBMPC DB9 pin 3)
Pin 3 -- RS232 TxData (transmits to IBMPC DB9 pin 2)
Pin 4 -- not used
Pin 5 -- Ground (must be grounded for RS422/485 operation)
Pin 6 -- RS422 Tx+
Pin 7 -- RS422 Tx-_ (for RS485, connect pins 6&8 and 7&9)
Pin 8 -- RS422 Rx+
Pin 9 -- RS422 Rx-