M172 losing PLC file

[POPE3909]

Hi Guys,

I have a M172 on site that has been running fine for at least 2-3 years without any issue. One day the controller stops doing its function and when I logged into it via Machine Expert HVAC, it says NO CODE at the bottom right corner. 

So, I tried doing a full download and download completed successfully but once I restart it, it goes back to NO CODE.
Then, I tried downloading only PLC code. After PLC only code download, I can do live-debug. But once I do a restart 'reboot target', it goes back to NO CODE.
What could be the problem? When I read the EEPROM registers after the restart, the values are still there so I assume the flash memory is still fine but somehow the PLC file keeps getting lost.

What could the likely cause for that? Thanks in advance.

[Bastian_Schmitz]

Hi,

Sounds like the flash memory of the controller is broken. I never seen this on TM172 but I see this behavior on TM171P in combination with data logging. Could you open the file system of the controller via Commissioning?

best regards

[POPE3909]

Hi Bastian,

Thanks for your reply. When I open the file system via Commissioning 'Open file brower', the PLC and HMI files seems to be still there. (see attached screenshot.) while ESME HVAC showing 'NO CODE'.