Insert a blank or newly formatted Siemens MMC into the PLC. When powered on, the PLC will attempt to load the empty configuration, effectively clearing the previous password-protected program. 3. Common Defaults
The S7-300 stores its configuration and passwords on a proprietary . If you have the physical card, you can often extract the password using an external Siemens USB Card Reader or a field PG.
Hold the mode selector switch in the position until the STOP LED lights up continuously (approx. 9 seconds).