To perform a passive format:

To unlock or reset a password-protected Siemens Simatic S7-300 PLC Go to product viewer dialog for this item.

🔄 Method 2: Hardware Factory Reset (MRES Destructive Method)

Place the MMC into a USB Prommer (such as the Siemens Field PG) and use STEP 7 to perform a "Factory Reset" or simply delete the contents of the MMC card, specifically the System Data folder.

For the S7-300 CPU, a memory reset using the physical key switch is the primary method to wipe the working memory, which effectively removes the password barrier. However, note that if one is inserted. To clear the MMC card, follow the steps below with the MMC inserted: