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DB-9 Connector Pinout

Below is the pinout of a typical 9 pin RS-232 connector, this connector type is also referred to as a DB-9 connector.

A computer's COM port (DTE) is usually male, and any peripheral devices you connect to this port usually have a female connector (DCE).

db-9 pinout

Pin Signal DTE Signal Direction Description
1 DCD IN Carrier Detect
2 RXD IN Receive Data
3 TXD OUT Transmit Data
4 DTR OUT Data Terminal Ready
5 GND - Signal Ground
6 DSR IN Data Set Ready
7 RTS OUT Request To Send
8 CTS IN Clear To Send
9 RI IN Ring Indicator