Comtrol DB25 - DB9 Pinouts; DB9 Loopback Plug; RS-232 Loopback Plug; RS-422 Loopback Plug

20 [Documentation number: 2000430 Rev B] Building Cables for DeviceMaster Products
DB9 Pinouts
DB9 Pinouts The following figure and table illustrates the DB9 connector signals.
Note: If you are using a DB9 to RJ45 adapter, see “RJ45 Serial Cables and
Loopback Plugs”, page 22 for additional information.
DB9 Loopback Plug A loopback plug is a DB9 female serial port plug with pins wired together. You can
use it with application software (for example, Test Terminal) to test serial ports.
This topic describes the following DB9 loopback plugs:
• An RS-232 loopback plug is shipped with the DeviceMaster Serial Hub.
• An RS-232/422 loopback plug is shipped with the following models:
DeviceMaster AIR, DeviceMaster PRO, DeviceMaster RTS, and DeviceMaster
UP.
Note: For more information on testing serial ports, see the Help in Test Terminal
(WCom2.exe). Test Terminal is installed when you install PortVision.
RS-232 Loopback
Plug
To build an RS-232 loopback plug, wire the following pins together:
•Pins 1 to 4 to 6
•Pins 2 to 3
•Pins 7 to 8 to 9
RS-422 Loopback
Plug
To build an RS-422 loopback plug, wire the following pins together:
•Pins 2 to 3
•Pins 7 to 8
Pinouts for Standard DB9 Connector
Pin RS-232 Mode RS-422 DCE Mode RS-485 Mode
1 DCD Not used Not used
2RxDRxD- Not used
3 TxD TxD- TxD/RxD-
4 DTR Not used Not used
5 GND Not used
a
a. Pin 5 is tied to ground on the board, but is not used in the cable.
Not used
a
6 DSR Not used Not used
7 RTS TxD+ TxD/RxD+
8CTSRxD+ Not used
9 RI Not used Not Used
Pin 1
Pin 5
Pin 6
Pin 9
DB9 Male for RS-232, RS-422, and RS-485
Pin 1
Pin 5
Pin 6
Pin 9
RS-232 Only
(Back View)
The RS-232 loopback plug
also works for RS-422.
Pin 1
Pin 5
Pin 6
Pin 9
RS-422 Only
(Back View)
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