2
Transmit Data
TD
From Printer
Serial data transmitted to the
system
3
Receive Data
RD
To Printer
Serial data received by the
printer
4
Request to Send
RTS
From Printer
Always set to low (mark)
5
Not Used
6
Data Set Ready
DSR
To Printer
Indicates that data can be
sent
7
Signal Ground
SG
Ground
Ground
8 to
10
Not Used
11
Supervisory Send
Data
SSD
From Printer
Indicates that the printer is
not ready to receive data
12 to
19
Not Used
20
Data Terminal
Ready
DTR
From Printer
Indicates that the printer is
not ready to receive data
21 to
25
Not Used
Commonly Used Serial Cable Configurations
IBM 25-Pin Cable Configuration