Comtrol Hub DeviceMaster - Manual (Page 101)

DeviceMaster Installation and Configuration Guide: 2000594 Rev. A Connecting Serial Devices - 101
Connecting Serial Devices
Serial Terminal (8)
Null-Modem Cables
(RS-422) An RS-422 null-modem cable is
required for connecting DTE
devices.
Serial Terminal (8)
Straight-Through
Cables (RS-232/485) RS-232 or RS-485 straight-
through cables are used to
connect modems and other
DCE devices.
Serial Terminal (8)
Loopback Signals Use the drawing below to wire a loopback, which is used in conjunction with
application software (Test Terminal or minicom) to test serial ports.
Wire the terminals together to
create a loopback.
• TxD to RxD
• RTS to CTS to RI
• DTR to CD to DSR
Note: You can use Test Terminal
(Windows) or minicom
(Linux) to test the serial
port. You can refer to
Testing Ports Using Test
Terminal
on Page 156 for Windows systems.
CD DSR RI DTR RTS TxD RxD CTS
RxD+ RxD- TxD- TxD+
8 2 3 7
5 3 2 4
DB9
DB25
RS-422 Null-Modem Cable
RS-232/485 Straight-Through Cable
CD DSR RI DTR RTS TxD RxD CTS
DCD DSR RI DTR RTS TxD RxD CTS
1 6 9 7 2 8
6 22 20 4 2 3 5
DB9
DB25
3 4
8
or
TRxD-
or
TRxD+
TxD RxD RTS CTS CD DSR RI DTR