Siemens alarm 400204: Restart required
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
A data block generated by the PLC basic program differs in size from the corresponding existing DB in the CPU. In contrast to the 4001xx family the system resolves this itself: at the next start-up the old DB is deleted and regenerated by the basic program with the correct geometry. No manual STEP 7 action is needed, but a restart must be accepted.
Likely causes
- Basic-program / NCK software step change left DBs of the previous version in memory
- Partial download updated code but not the associated instance/data blocks
Triage note: Official remedy: the DB is deleted and regenerated by the basic program during next start-up.
Need the part urgently?
Send us alarm 400204 with your machine details — typical RFQ turnaround is 24–48h.