Comtrol 16-Port - Manual (Page 4)

Hardware Installation 4
DB25 Interfaces
DB25 Interfaces Use the following information for DB25 connectors.
Standard interface boxes use female connectors, while the
Surge interface boxes use male connectors.
This table shows connector information for connectors.
Building DB25
Female Loopback
Plugs Loopback plugs are used with the diagnostics to test serial ports.
Wire the following pins together for an RS-422
loopback plug (Surge interface box).
• Pins 15 to 19
• Pins 17 to 25
Building DB25 Male
Loopback Plugs Loopback plugs are used with the diagnostics to test
serial ports.
This loopback plug is used with the standard 8- and
16-port DB25 interface boxes.
• Pins 2 to 3
• Pins 4 to 5 to 22
• Pins 6 to 8 to 20
Wire the following pins together for an RS-422
loopback plug.
• Pins 15 to 19
• Pins 17 to 25
Pin RS-232 Signal RS-422 Signal
1 Not used Not used
2 TxD Not used*
3 RxD Not used*
4 RTS Not used*
5 CTS Not used*
6 DSR Not used*
7 Signal ground Signal ground*
8 DCD Not used*
9 to 14 Not used Not used
15 Not used RxD+
16 Not used Not used
17 Not used RxD-
18 Not used Not used
19 Not used TxD+
20 DTR Not used*
21-24 Not used Not used
25 Not used TxD-
* All RS-232 signals are present in RS-422 mode.
Pin 13 Pin 1
Pin 25 Pin 14
DB25 Female
Pin 14 Pin 25
Pin 1 Pin 13
DB25 Male
Pin 25 Pin 14
Pin 13 Pin 1
RS-422 Only (Back View)
Pin 13 Pin 1
Pin 14 Pin 25
RS-232 Only (Back View)
Pin 25 Pin 14
Pin 1 Pin 13
RS-422 Only (Back View)