DB25 pinout and signals for the PC RS232 connector (serial and COM ports)

DB25 pin D-SUB male at the DTE (Computer)
DB25 pin D-SUB male

Pin Name Direction 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).

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