Unlock S7-300 Plc Password Better

Hold the selector switch in the MRES position until the STOP LED blinks, release, and hold again.

These passwords are often stored on the Micro Memory Card (MMC) rather than the volatile RAM of the CPU itself. Method 1: Using the Original Project Source unlock s7-300 plc password

In SIMATIC Manager, export the locked block as a source file (.AWL). Edit the Source: Open the .AWL file in a text editor (like Notepad++). Delete the Keyword: Look for the line KNOW_HOW_PROTECT in the header and delete it. Re-import: Hold the selector switch in the MRES position