Siemens alarm 400006: Loss of remanent PLC data

What it means

Retentive PLC data (markers, counters, data kept across power-off) could not be restored at start-up - for example because the backup time was exceeded or power-up ran with default data. The affected data must be re-entered before production resumes.

Likely causes

• Power-up with factory defaults or after standard-PLC deletion
• Remanent data not backed up before service action
• Extended storage without power exceeding retention