Interface operating manual Appendix I. Pin assignment RS 232 pin # direction IBM AT 2 3 5 6 8 → ← ↔ → → RxD TxD Gnd DSR CTS 6 1 9 5 RS232 RS 422 pin # direction ax422 convert 2 Tx3 Tx+ 4 Rx5 Rx+ → → ← ← RxRx+ TxTx+ 23 45 RS422 Page 34