RS232

(At the DTE)
(At the DCE)

25 PIN D-SUB MALE at the DTE (Computer).
25 PIN D-SUB FEMALE at the DCE (Modem).

Pin	Name	ITU-T	Dir	Description
1	GND	101		Shield Ground
2	TXD	103		Transmit Data
3	RXD	104		Receive Data
4	RTS	105		Request to Send
5	CTS	106		Clear to Send
6	DSR	107		Data Set Ready
7	GND	102		System Ground
8	CD	109		Carrier Detect
9	-		-	RESERVED
10	-		-	RESERVED
11	STF	126		Select Transmit Channel
12	S.CD	?		Secondary Carrier Detect
13	S.CTS	?		Secondary Clear to Send
14	S.TXD	?		Secondary Transmit Data
15	TCK	114		Transmission Signal Element Timing
16	S.RXD	?		Secondary Receive Data
17	RCK	115		Receiver Signal Element Timing
18	LL	141		Local Loop Control
19	S.RTS	?		Secondary Request to Send
20	DTR	108		Data Terminal Ready
21	RL	140		Remote Loop Control
22	RI	125		Ring Indicator
23	DSR	111		Data Signal Rate Selector
24	XCK	113		Transmit Signal Element Timing
25	TI	142		Test Indicator