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M91 wire guide - System fault Power in failure

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I am new to this, just got given a m91-2-ra22 unit and been asked to get the program from the plc.

I have 24v power supply connected to the top input and it power and i can communicate with it over rs232.

The unit is showing system fault. Power in failure.

Is there a way to fix this?

Ive never used these units before.

Thank you

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5 hours ago, Parrey said:

The unit is showing system fault. Power in failure.


1. "unit is showing system fault" - How fault looks?

2. "Power in failure" - How failure looks? Is this related to p. 1?

Pictures, text, more explanation...

3. When this fault happens?

4. Is this setup new or old?

5. Being this setup working before?

6. How problem started?

Details, details, details...



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  • MVP 2023

As you can communicate via 232, in theory you can use U90 to try and get the program out of the unit for you to then examine.  If successful, I am guessing that one of the inputs is used to monitor whether power of a certain type is on, and this is raising what I think will be a screen that is part of the user program in the unit.  As Alex says, not quite enough detail.

U90 has lots of help to assist your learning.

cheers, Aus

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  • 2 weeks later...

Sorry i have been away and have just got home.

I was able to pull the program off using rs232.

I have a look into the program and in6 was a power failure relay which was checking for 24v.

I added a 24v input to it and the errors went away and i was able to use the unit fully.

Thank you all for your help

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