Serial (RS232) printer. Pinout and signals for the serial printer connector

DB25 pin D-SUB male at the printer
DB25 pin D-SUB male (at the printer)

Pin Name Direction Description
1
SHIELD
Shield Ground
2
TXD
—»
Transmit Data
3
RXD
«—
Receive Data
4
n/c
-
Not connected
5
n/c
-
Not connected
6
DSR
«—
Data Set Ready
7
GND
System Ground
8
DCD
«—
Data Carrier Detect
9
n/c
-
Not connected
10
n/c
-
Not connected
11
?
—»
Reverse Channel
12
n/c
-
Not connected
13
n/c
-
Not connected
14
n/c
-
Not connected
15
n/c
-
Not connected
16
n/c
-
Not connected
17
TTY-TXD
—»
TTY Receive Data
18
n/c
-
Not connected
19
n/c
-
Not connected
20
DTR
—»
Data Terminal Ready
21
n/c
-
Not connected
22
n/c
-
Not connected
23
?
—»
TTY Receive Data Return
24
?
«—
TTY Transmit Data Return
25
TTY-RXD
«—
TTY Receive Data