11
3.1 Serial Port Pin-Out Information of DB9 Connector
Pin Number
Pin Type
Description
1
Input
DCD Data Carrier Detect
2
Input
RxD Receive Data
3
Output
TxD Transmit Data
4
Output
DTR Data Terminal Ready
5
Ground
GND Signal Ground
6
Input
DSR Data Set Ready
7
Output
RTS Request To Send
8
Input
CTS Clear To Send
RS-232 pin-out for DB9 connector
Pin Number
Pin Type
Description
1
Output
TxD- Transmit Data, negative polarity
2
Output
TxD+ Transmit Data, positive polarity
3
Input
RxD+ Receive Data, positive polarity
4
Input
RxD- Receive Data, negative polarity
5
Ground
GND Signal Ground
RS-422/485 full duplex pin-out for DB9 connector
Pin Number
Pin Type
Description
1
Output/Input Data- Transmit/Receive Data, negative polarity
2
Output/Input Data+ Transmit/Receive Data, positive polarity
5
Ground
GND Signal Ground
RS-485 half duplex pin-out for DB9 connector
