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M91 RS-232 RJ11 to RJ45 Serial Communication

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I have a M91 Unitronics PLC (M91-T4-R6-ZK1 serial HB21006HN4002G) which has a RJ-11 port for RS-232 Modbus communication.

I have a GE PLC which has a RJ-45 port for RS-232 communication with following pin readout:


Is a adapter kit required?

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  • MVP 2023

You're going to have to make a cable, but it should work.

On the Unitronics side-

3 - TX

4 - RX

5 - COM (0V)

Search the Help for "RS232" and choose the RS232 topic for a picture.

Cross TX and RX in your cable:

GE        M91

2            4

3            2

5           5


Joe T.


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Thanks for the reply. Sounds like I can use a RJ11 (phone) cable and add a RJ-45 connector or vice versa.

Did you mean (see underline)

GE        M91

2            4

3            3

5           5


I was looking for the picture you mentioned and could not find the RS232 topic.

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