15
Pin Assignments
COM Port/Interface
Signal
Direction
Pin #
DCE Transmit Clock ( TXC )
From DCE ( Out )
1
DCE Received Data ( RXD )
From DCE ( Out )
2
Signal Ground ( SG )
—
3
DCE Transmit Data ( TXD )
To DCE ( In )
4
DCE Data Terminal Ready ( DTR )
To DCE ( In )
5
DCE Carrier Detect ( CD )
From DCE ( Out )
6
DCE Request to Send ( RTS )
To DCE ( In )
7
DCE Received Clock ( RXC )
From DCE ( Out )
8
EIA-232E DTE Ports/Interfaces
Signal
Circuit
Mnemonic
ITU/
CCITT #
Direction
25-Pin
EIA-232E
Pin #
Shield
—
—
—
1
Transmitted Data ( TXD )
BA
103
To DCE
2
Received Data ( RXD )
BB
104
From DCE
3
Request to Send ( RTS )
CA
105
To DCE
4
Clear to Send ( CTS )
CB
106
From DCE
5
Data Set (or DCE ) Ready
( DSR )
CC
107
From DCE
6
Signal Ground/Common ( SG )
AB
102A
—
7
Received Line Signal Detector
( RLSD or LSD )
CF
109
From DCE
8
Reserved for future use
—
—
—
9
Not used
—
—
—
10
Reserved for future use
—
—
—
11
Reserved for future use
—
—
—
12
