Hardware Style Owner's manual

Appendix C
RS-232 Communication Interface
C–4
DTE Pinout
Channel 0, which the 5/03 processor has, is configured as DTE. The pinouts
are the same as the 9–pin AT port.
DTE 9 pinout Signal is
Equivalent
DTE 15 pinout
Equivalent
DTE 25 pinout
1 -DCD Data Carrier Detect Input 8 8
2 -RXD Received Data Input 3 3
3 -TXD Transmitted Data Output 2 2
4 -DTR Data Terminal Ready Output 11 20
5 -COM Common Return (Signal Ground) Shared 7 7
6 -DSR Data Set Ready Input 6 6
7 -RTS Request to Send Output 4 4
8 -CTS Clear to Send Input 5 5
9 -NC No Connection Input 22 RI Ring Indicator
DCE Pinout
Devices such as a modem are DCE. The pinouts on these terminals are
wired to interface with DTE.
DCE 9 pinout Signal is
Equivalent
DCE 25 pinout
1 -DCD Data Carrier Detect Output 8
2 -RXD Received Data Output 3
3 -TXD Transmitted Data Input 2
4 -DTR Data Terminal Ready Input 20
5 -COM Common Return (Signal Ground) Shared 7
6 -DSR Data Set Ready Output 6
7 -RTS Request to Send Input 4
8 -CTS Clear to Send Output 5
9 -RI Ring Indicator Output 22
Important: DCE signal names are viewed from a DTE perspective. For
example, TXD is a DTE output and also a DCE input.