Aaeon SBC-400 User Manual page 34

RS-422
RS-485
The following table shows the pin assignments for the card's RS-
232 and RS-422/485 (COMB) serial port connectors:
Pin Signal
1 DCD
2 RX
3 TX
4 DTR
5 GND
6 DSR
7 RTS
8 CTS
9 RI
RS-422 is used for long-distance point-to-point connections. RS-
422 originally used four wires for one-way communication (with
devices such as display terminals or printer) but was later adopted
Pin Signal
1 TX- (DTE)
2 TX+ (DTE)
3 RX+ (DTE)
4 RX- (DTE)
5 Ground
6 RTS-
7 RTS+
8 CTS-
9 CTS-