Specifications
62 - Connecting Serial Devices DeviceMaster Installation and Configuration Guide: 2000506 Rev. B
RJ45 Null-Modem Cables (RS-422)
RJ45 Null-Modem
Cables (RS-422)
Use the following figure if you need to build an RS-422 null-modem RJ45 cable. A null-
modem cable is required for connecting DTE devices.
Note: RS-422 pinouts are not standardized. Each peripheral manufacturer uses different
pinouts. Please refer to the documentation for the peripheral to determine the
pinouts for the signals above.
Straight-Through
Cables (RS-232/485)
Use the following figure if you need to build an RS-232 or RS-485 straight-through cable.
Straight-through cables are used to connect modems and other DCE devices. For example,
a straight-through cable can be used to connect COM2 of one PC to CO M2 to a m odem .
RJ45 Loopback Plugs Loopback connectors are RJ45 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 is shipped with a a single loopback plug (RS-232/422).
•Pins 4 to 5
•Pins 1 to 8
• Pins 2 to 6 to 7
Note: You can use Test Terminal
(Windows) or minicom
(Linux) to test the serial
ports. You can use the Support page on the CD shipped with the DeviceMaster or see
Locating Software and Documentation
on Page 10) to locate the NS-Link User Guide
for Windows or the Linux readme file.
RS-485 Test Cable You can use a straight-through cable as illustrated previously, or build your own cable.
Note: RS-422 pinouts are not standardized. Each peripheral manufacturer uses different
pinouts. Please refer to the documentation for the peripheral to determine the
pinouts for the signals above.
DeviceMaster
TxD+
TxD-
RxD+
Signal
RJ45
1
4
8
Pins
Female
RxD+
RxD-
Signal
RxD- 5
TxD+
TxD-
DeviceMaster
DB9
1
2
3
4
5
8
6
7
Pins
DCD
RxD
TxD or TRxD-
DTR
GND
CTS
DSR
RTS or TRxD+
Signal
DCD
RxD
TxD or TRxD-
DTR
GND
CTS
DSR
RTS or TRxD+
Signal
Female
RI
9RI
RJ45
6
5
4
2
3
8
7
1
Pins
N/A
RJ45
6
5
4
2
3
8
7
1
Pins
N/A
DB25
8
3
2
20
7
5
6
4
Pins
22
18
Plug
Top View
Cable
The RS-232 loopback plug also
works for RS-422.
TRxD-
TRxD+
Signal
TRxD-
TRxD+
Signal
RJ45
4
1
Pins