PC serial (25 pin)

25 pin D-SUB male connector at the computer

Pin	Name	Dir	Description
1	SHIELD	-	Shield Ground
2	TXD		Transmit Data
3	RXD		Receive Data
4	RTS		Request to Send
5	CTS		Clear to Send
6	DSR		Data Set Ready
7	GND	-	System Ground
8	CD		Carrier Detect
9	n/c	-
10	n/c	-
11	n/c	-
12	n/c	-
13	n/c	-
14	n/c	-
15	n/c	-
16	n/c	-
17	n/c	-
18	n/c	-
19	n/c	-
20	DTR		Data Terminal Ready
21	n/c	-
22	RI		Ring Indicator
23	n/c	-
24	n/c	-
25	n/c	-

Note: Direction is DTE (Computer) relative DCE (Modem).
Note: Do not connect SHIELD(1) to GND(7).