Incorrect checksum of B & R module when downloading program and DIAG mode

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1

Hello All.
Recently I’ve got a problem that I can’t anymore download software to PLC X20CP3687X.
Sometimes it works, but usually not.
The problem is that after download PLC goes into DIAG mode. The reason is “Incorrect B & R module checksum” ID 6405 ROOT.
What help me is to remove memory card and load program offline.
Can you suggest something where I can lock into?
Thanks a lot!

2

Hi Sergei,

checksum errors could be caused by hidden page faults e.g. some code overwrites the memory where the module is stored in DRAM.

During download the _INIT code of of programs is executed while other programs are still running their cycles. This may be the cause why you only get this during project download and not after warmstart.

so all tips of this topic could help:

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3

Hello Christoph. Problem is only when I download and need to restart PLC. If I download without restart needed all is OK.
So something wrong only after program download and restart.
I tried already to remove all permanent tags from configuration. Without success.
And only if I remove card and install project offline I’m able to bring PLC to RUN mode automatically.

4

Hi Sergei,

According to the online help, 6405 is entered if the precalculated checksum of the B&R module is not corrected, i.e. the file of the module is corrupt. This is detected during start-up.
This error cannot be ‘repaired’ unless the file is rewritten (e.g. by writing to the flash).

https://help.br-automation.com/#/en/6/diagnostics_support%2Fsys_error%2Ffiles%2Fsyserror_br2000_6405.htm

In contrast to that, there is error 6403, which is entered if the module in DRAM was destroyed during runtime.

https://help.br-automation.com/#/en/6/diagnostics_support%2Fsys_error%2Ffiles%2Fsyserror_br2000_6403.htm

In this respect, it can be assumed that ‘something’ destroys your file system during or directly after the download.

In both cases, a page fault could be the cause.

Possible remedy:

  • Use the ‘safe file system’
  • Use IEC Check / AdvIecCheck library

Do not hesitate to contact the local B&R support. Further questions may arise:

  • are always the same module(s) affected
  • which module types are affected
  • are the affected modules created during runtime (e.g. data objects)
  • are there some more logger entries

btw:

Do you already know ‘AdvIECcheck’ library ? (unfortunately not helpful when using C/C++)

5

Hello All. Just an update.
We tried a lot of things what you had suggest but without success.
Then we tried to exchange existing 512 MB memory card with 1GB.
After that exchange we have no more problems.
It is sad that B&R have no clear message for that.
We check before and after load of program in SDM manager - all memory capacity was OK. We as well tried several cards 512MB.
So the only one thing help us - 1GB memory card.
Best Regards
Sergei

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6

Hi Sergei,

I’ve no clear information how download is done physically.
But I could imagine a task would need double the memory during overload, e.g. first save the new file and then delete the old one. So flash space could matter.

But that would require us to step much deeper into your problem than is possible in this community.

So the best way is still to contact the local support if the solution is not satisfying for you.

But thank you for the feedback. It may help someone else later !

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