odot ODOT-S1E1V2.0, User Manual, Page: 26 / 29

http:// www.odotautomation.com
26 / 29
TEL: +86-0816-2538289
9-pin RS232 serial port （ DB9 ）
Pin Name Function
1 CD Carrier detect
2 RXD Receive data
3 TXD Send data
4 DTR Data terminal ready
5 GND Signal ground
6 DSR Data ready
7 RTS Request to send
8 CTS Clear to send
9 RI Ring alert
As the RS232 interface has the above electrical characteristics, it can only realize
point-to-point communication.
RS232 communication wiring diagram is shown in the figure below:
2. RS422
The full name of RS422 interface standard is "Electrical Characteristics of
Balanced Voltage Digital Interface Circuit", which defines the characteristics of the
interface circuit. RS422 adopts four-wire plus ground wire (T+, T-, R+, R-, GND),
full-duplex, differential transmission, multi-point communication data transmission
protocol. It USES a balanced transmission line that is unidirectional/non-reversible,