The Siemens S7-200 uses four distinct levels of protection, configured within the using STEP 7-Micro/WIN software:
This tool is typically found on the original STEP 7-Micro/WIN installation CD. 3. Hardware Factory Reset (MRES)
If you are locked out of an S7-200, Siemens provides official recovery paths. Note that these methods generally involve to regain control of the hardware. 1. The "CLEARPLC" Universal Reset
If you simply need to reuse the PLC hardware and do not need the existing program, you can perform a memory reset using the universal override password: Open and go to the PLC > Clear menu. Select all blocks (Program, Data, and System).
When prompted for a password, enter CLEARPLC (not case-sensitive).
It resets the baud rate to 9.6 kbit/s and the network address to 2 , returning the CPU to its pristine delivery state.