DB9 pinout and signals for the PC RS232 connector (serial and RS232 ports)

DB9 pin D-SUB male

Pin	Name	Direction	Description
1	CD	←	Carrier Detect
2	RXD	←	Receive Data
3	TXD	→	Transmit Data
4	DTR	→	Data Terminal Ready
5	GND		System Ground
6	DSR	←	Data Set Ready
7	RTS	→	Request to Send
8	CTS	←	Clear to Send
9	RI	←	Ring Indicator

Note: Direction is DTE (Computer) relative DCE (Modem).

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