If you must preserve the program, you need to extract the password from the Micro Memory Card. Since the S7-300 stores the password in a specific hex block on the MMC, specialized tools are often required. The S7-Block Privacy Bypass
Bypassing or resetting passwords on industrial control systems can lead to a complete loss of the stored program, data, and machine parameters. Always ensure you have appropriate authorization and a fallback plan before attempting these procedures.
These tools scan the image for the stored password string (up to 8 characters) and display it.
The S7-300 series utilizes three distinct protection levels configured in Simatic Manager TIA Portal Level 1 (No Protection): Full read and write access for all users. Level 2 (Read Protection):