RS232, RS422 & RS485 standard DB connector pinout

RS232 pinout

RS232 pinout standards exist for both DB9 and DB25 connectors as shown below:

DB25	SIGNAL	DB9	DEFINITION
1			Protective Ground
2	TXD	3	Transmitted Data
3	RXD	2	Received Data
4	RTS	7	Request To Send
5	CTS	8	Clear To Send
6	DSR	6	Data Set Ready
7	GND	5	Signal Ground
8	CD	1	Received Line Signal Detector
9			Reserved for data set testing
10			Reserved for data set testing
11			Unassigned
12	SCF		Secndry Rcvd Line Signl Detctr
13	SCB		Secondary Clear to Send
14	SBA		Secondary Transmitted Data
15	DB		Transmisn Signal Timng
16	SBB		Secondary Received Data
17	DD		Receiver Signal Element Timing
18			Unassigned
19	SCA		Secondary Request to Send
20	DTR	4	Data Terminal Ready
21	CG		Signal Quality Detector
22		9	Ring Indicator
23	CH/CI		Data Signal Rate Selector
24	DA		Transmit Signal Element Timing
25			Unassigned