Rj45 Null-Modem Cables (Rs-422); Rj45 Straight-Through Cables (Rs-232/485); Rj45 Loopback Plugs; Rj45 Rs-485 Test Cable - Comtrol DeviceMaster PNIO 2000 Series User Manual

Connecting Serial Devices
RJ45 Null-Modem
Cables (RS-422)
RJ45 Straight-
Through Cables (RS-
232/485)
RJ45 Loopback
Plugs
RJ45 RS-485 Test
Cable
42 - Connecting Serial Devices
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.
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 COM2 to a modem.
Signal
DCD
RxD
TxD or TRxD-
DTR
GND
DSR
RTS or TRxD+
CTS
Loopback connectors are RJ45 serial port plugs with pins wired together that are
used in conjunction with application software to test serial ports. The
DeviceMaster UP 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
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.
RJ45
Signal
Pins
TxD+
1
TxD- 4
RxD+ 8
RxD- 5
GND 3
RJ45
RJ45 DB9
Pins
Pins Pins
6 1 6
2 5
5
3 4
4
2
2 4
3
3 5
7
7 6
7 1
1
8
8 8
1 8
Plug
Top View
Cable
RJ45
Signal Pins Signal
4
TRxD-
1
TRxD+
DeviceMaster PNIO | UP User Guide: 2000639 Rev. A
Signal
RxD+
RxD-
TxD+
TxD-
GND
DB25
Pins Signal
8
DCD
3
RxD
2
TxD or TRxD-
20
DTR
7
GND
6
DSR
4
RTS or TRxD+
5
CTS
The RS-232 loopback plug also
works for RS-422.
TRxD-
TRxD+