If you do not need to recover the existing program and simply want to reuse the expensive MMC hardware, you can reset the card directly inside an S7-300 CPU. Insert the locked MMC into the S7-300 CPU slot.
Enter CLEARPLC when prompted for the password authorization. simatic s7 200 s7 300 mmc password unlock 2006 09 11
: The system encrypts this password data and compiles it directly into specific configuration blocks—predominantly inside SDB 0000 —which load directly upon CPU initialization. Authorized Reset Methods (Data Loss Required) If you do not need to recover the