For newer firmware (>V2.5), hardware attacks become necessary. The S7-200 SMART CPU uses a TI ARM Cortex-M3 or M4 processor (depending on model: ST20, SR40, etc.). These have a Serial Wire Debug (SWD) interface.
If communication is blocked or the PLC is locked at Level 4, you can use a physical reset via a MicroSDHC card Siemens SiePortal Create a "transfer card" using a standard MicroSD card. Place an empty file or a specific reset command file ( S7_JOB.S7S ) on the card. Power off the PLC, insert the card, and power it back on. Wait for the LED indicators
: Running this utility will delete the user program, data blocks, and configuration information.
No password is required for any operation.
The S7-200 SMART (firmware V2.0 to V2.8) implements a three-tier protection system: