I have just encountered the same error with a S7-1215C after months of usage.
Part of my diagnostic buffer (see attached file for complete buffer):
1 of 50; Event ID: 16# 02:401A
CPU info: Serious firmware exception
(not relevant for user, system code: 16#00644A4E 16#10000034 16#080D0000)
|> CPU changes from RUN to DEFECTIVE mode
|> HW_ID= 52 - Operating mode control
I have tried to power cycle the CPU, but the problem reappears as soon as I try to download a hardware configuration. I have just tried with a totally fresh and empty project as well. And with and without the memory card inserted.
I wonder if the error is related to this:
-I did try to upgrade the firmware about a week ago from the CPU web page, but it kept on failing after a few minutes of uploading:
|Error:||The firmware update file failed to be written. Please try again.|
I wonder if a 8 MB SMC card is necessary, as the firmware file is on 5 MB, and I only have a 2MB SMC (the black Siemens Memory Cards 954 series). Do I need a memory card to upgrade the firmware? It doesn't say on the firmware pages.