Rj45 Null-Modem Cables (Rs-422); Rj45 Straight-Through Cables (Rs-232/485); Rj45 Loopback Plugs; Rj45 Rs-485 Test Cable - Comtrol DeviceMaster EIP Series Hardware Installation And Configuration Manual

Connecting Serial Devices

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 pin outs are not standardized. Each peripheral manufacturer uses different pin outs. Please
refer to the documentation for the peripheral to determine the pin outs for the signals above.

RJ45 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 COM2 to a modem.

RJ45 Loopback Plugs

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 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
Not all DeviceMaster protocols provide test (example
programs). Refer to the
information about using those example programs.

RJ45 RS-485 Test Cable

You can use a straight-through cable as illustrated previously, or build your own cable.
Note: RS-422 pin outs are not standardized. Each peripheral manufacturer uses different pin outs. Please
refer to the documentation for the peripheral to determine the pin outs for the signals above.
40 - Connecting Serial Devices
Signal
TxD+
TxD-
RxD+
RxD-
GND
RJ45
Signal Pins
6
DCD
5
RxD
4
TxD or TRxD-
2
DTR
3
GND
DSR 7
1
RTS or TRxD+
8
CTS
EtherNet/IP User Guide
Signal
TRxD-
TRxD+
DeviceMaster EIP | UP Hardware Installation and Configuration Guide: 2000633 Rev. C
RJ45
Pins
Signal
RxD+
1
4
RxD-
8 TxD+
5
TxD-
3
GND
DB9 RJ45 DB25
Pins
Pins Pins
6
1 8
2 5
3
3 4
2
4 2 20
3
5 7
6 7
6
7 1
4
8 8
5
1
Plug
Top View
Cable
for
RJ45
Pins Signal
4
TRxD-
1
TRxD+
Signal
DCD
RxD
TxD or TRxD-
DTR
GND
DSR
RTS or TRxD+
CTS
The RS-232 loopback plug also
8
works for RS-422.