CPU went into Stop Mode

I am a Siemens rookie...looking for suggestions.

We had a 6ES7-516-3AN00-0AB0 running firmware v1.7 go into stop mode the other day for no apparent reason. It had been operating fine up to that point. The weather was bright and sunny no storms. It was kind of like it put it back to the default mode as the diagnostic buffer was pretty much wiped clean showing the date as 2011. The program was still intact though which is odd. Any ideas on what could be the cause of this to happen. I can’t even pull the diagnostic because there is nothing there. Any insight would be greatly appreciated.

Thanks 

Hi,

Since there is no obvious clues about the reason, then I would suggest to upgrade the cpu with the newest firmware.

You mention it is currently v1.7. The newest firmware for your model is 1.8.5.

It can be downloaded at:

Firmware Update for CPU 1516-3 PN/DP

After upgrading the firmware, you do not absolutely need to change the firmware version in the project, but I do recommend it.