Connect via a PC/PPI cable and try common default passwords or historical company codes.
This method allows you to clear the memory blocks without knowing the specific user-set password. Open STEP 7-Micro/WIN software. Navigate to the PLC menu and select Clear . Select all three blocks (Program, Data, and System). Siemens S7-200 Password Unlock
When prompted for a password, enter CLEARPLC (not case-sensitive). This will reset the PLC to factory defaults while maintaining its address and baud rate. Connect via a PC/PPI cable and try common