: These methods are destructive. If you do not have a backup of the original code, the logic will be permanently lost once the PLC is cleared. Unauthorized Tools
Most likely a cable issue. Real Siemens PPI cables have a built-in level shifter (RS232 to RS485). Cheap USB-serial adapters without proper PPI timing will not work. Also, ensure the CPU is in STOP mode (some tools require STOP to read memory). siemens s7 200 smart password unlock