ML1400 - MSG error 021

[Mowgli86]

Hi all,

I have an odd error with a set of MSG commands. I have 14 different MSG commands, each with their own routing info file. They are sending or receiving CIP generic messages to a variable frequency drive over ethernet. It's been working on all my systems for months and never had a problem. However something has happened to the latest one, where a minor change to a completely unrelated part of the code (for example changing a comparison from 'equal to' to 'greater than' results in all the message functions returning the same error:

021: Bad Parameter in MSG file, command could not be built by local processor'

If I then reverse the change I made and download again, the error remains. The only way to get the system working again is the revert to the original file and download that.

It doesn't seem logical, as there have been no changes to any part of the file relating to MSG functions. The memory in the PLC is only about 20% used, so plenty of room there, and the Channel configs haven't changed either.

One thing I noticed is that the LBN (Local Bridge Node) is -1 in the working file, but 0 in the non working file. This is a read-only parameter so I think it's possibly changing as a result of the error, rather than being a cause of it.

Would be very grateful for any thoughts!

Thanks,

 

[Mowgli86]

I've ruled out any external changes, and I am trying to pin down the differences between a working file and a non-working one. I created a new MG data file, and recreated the same messages in a new file. Strangely, the greyed out 'Local/Remote' is set to Remote is the working version (as above), but when I create an otherwise identical MSG, that is set to Local, and I can't edit it. Same CIP Generic command, same Generic Get/Set Attribute Single. With the latter version, the messages are not received by the external device at all.

I'm at a loss to find any differences which might be causing this!

 

[Mowgli86]

Quick update - I swapped the PLC with a new one to rule out a hardware fault, but, perhaps unsurprisingly, the fault remains the same.

 

[Donnchadh]

Hi
Have you used the compare tool as its very good in logic 500
Could you post both programms so maybe we could go through them
Have you the same amount of message blocks in both programs

Donnchadh

 

[Mowgli86]

Hi Donnchadh,

Thanks for your reply. I will need to strip out a bit of the confidential data before I can post the programs up, but thank you for offering to look through them.

I wasn't aware of a compare function so will certainly look into that - I am using RS Logix Micro, not 500 however.

There are exactly the same message blocks in each program.

Cheers,

Mowgli

 

[Mowgli86]

The Compare function picked up 'HTTP Server Enable' (in Channel Config, Channel 1) being unchecked in the working version, but checked in the non-working version. Seems like this might be the cause! I have no idea what it does though (off to the manual again )

 

[SteriflowMatt]

MSG error 021

Hi Mogli86,

I know it has been a long time, but I had had the same problem in a program that I was re-using and ran across this thread.

My problem wound up being that the message was changed from a local to a remote message. I'm not sure how that happened, but your picture also shows a remote message. Maybe it is supposed to be like that in your case, but if your VSDs are on the same subnet, then you will get that error message.

Fixing was easy - identical copies of the message instructions, which came out as local messages, put in place of the remote ones.

Again, it has been a long time, but this might help someone.

Cheers,

Matt

 

[Campbetc]

MSG error 021

Thanks SteriflowMatt!

Changing from a remote message to local worked for me. It was an easy fix, just annoying to recreate the MSG instructions.

Thanks,

Campbetc