Unlocking passwords for Siemens Simatic S7-200 and S7-300 PLCs usually refers to two distinct needs: a forgotten password to keep the existing program, or wiping the device to reuse the hardware. 1. S7-300 MMC Password Recovery (The "2006/2009" Method)
Hardware Reset : Power down the CPU, hold the MRES button, and power it back up. Continuing to hold the button for 5 seconds will trigger a memory clear, effectively removing the hardware-level password. : For Go to product viewer dialog for this item. hold the MRES button
Most of these utilities were distributed in compressed formats like .rar on specialized engineering forums. Critical Warnings and Risks hold the MRES button