Hi,

I know, the "official" MMC 2 MB card for this CPU (6ES7 151-7AA21-0AB0) is the 6ES7953-8LL20-0AA0, according to this Siemens article (https://support.industry.siemens.com/cs/document/35000903/which-memory-cards-are-used-in-the-interface-modules-in-the-et-200-with-cpu-functionality?dti=0&lc=en-WW).

I have a 6ES7953-8LL10-0AA0 MMC card and it's not working (the STOP LED flashes slow and cannot reformat the card, regardless how many different ways I toggle the mode switch into the MRES position).

Is the 6ES7953-8LL10-0AA0 definitely incompatible with this CPU?

Thank you,

Hello,

8LL10 is 'old' MMC. Basically the compatibility depends from the firmware version of CPU. 

The most important thing: you should be sure that the card is not damaged. And ask directly Support Request. Write also the MLFB number and actual firmware version of the CPU.

Best regards,

Hristo Mihalev