C2904M-B (2/05) 13
PIN ASSIGNMENTS
Pin COM1 COM2
RS-232 RS-232/485 RS-232
1DCD –
(data carrier detect)
2RxD RxD+ RxD
(receive data) (receive data plus) (receive data)
3TxD TxD- TxD
(transmit data) (transmit data minus) (transmit data)
4DTR –
(data terminal ready)
5GND (ground) GND (ground) GND (ground)
6DSR –
(data set ready)
7RTS TxD+
(ready to send) (transmit data plus)
8 CTS RxD-
(clear to send) (receiver data minus)
9–––
1 2 3 4 5
6 7 8 9