Db9 Serial Cables And Loopback Plugs; Db9 Loopback Plugs - Comtrol DeviceMaster Up Hardware Installation Manual

DB9 Serial Cables and Loopback Plugs

DB9 Loopback Plugs

Connecting Serial Devices
You can build your own null-modem or straight-through DB9 serial cables using
the following subsections.
Pin
† Pin 5 is tied to ground on the board, but is
This illustrates the DB9 connector signals.
RS-232
GND
RI
DTR
CTS
TxD
RTS
RxD
DSR
CD
Pin 6
Pin 1
DB9 Male
Note: If you are using a DB9 to RJ45 adapter, see
Loopback Plugs
Loopback connectors are DB9 female serial port plugs, with pins wired together as
shown, that are used in conjunction with application software (Test Terminal or
Minicom) to test serial ports. The DeviceMaster UP is shipped with a a single
loopback plug (RS-232/422).
Wire the following pins together to build additional plugs or replace a missing RS-
232 loopback plug:
• Pins 1 to 4 to 6
Pin 1
• Pins 2 to 3
• Pins 7 to 8 to 9
Wire the following pins together for an RS-422 loopback plug:
• Pins 2 to 3
• Pins 7 to 8
DB9 Connector Pinouts
RS-232 RS-422
1 DCD Not used
2 RxD RxD-
3 TxD TxD-
4 DTR Not used
5 GND Not used†
6 DSR Not used
7 RTS TxD+
8 CTS RxD+
9 RI Not used
not used in the cable.
RS-422
Not used*
Not used
Not used
RxD+
TxD-
TxD+
RxD-
Not used
Not used
Pin 6
Pin 1
DB9 Male
* Pin 5 is tied to ground on the board,
on Page 29.
Pin 5
RS-232 Only
(Back View)
Pin 6 Pin 9
Pin 5
Pin 1
Pin 6 Pin 9
DeviceMaster UP User Guide: 2000451 Rev. C - 27
DB9 Serial Cables and Loopback Plugs
RS-485
Not used
Not used
TxD/RxD-
Not used
Not used†
Not used
TxD/RxD+
Not used
Not Used
RS-485
Not used*
Not used
Not used
Not used
TxD/RxD-
TxD/RxD+
Not used
Not used
Not used
Pin 6
Pin 1
DB9 Male
but is not used in the cable.
RJ45 Serial Cables and
The RS-232 loopback plug
also works for RS-422.
RS-422 Only
(Back View)