Siemens alarm 400102: Delete DB 2 in the PLC and restart
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
The length of data block DB2 in the PLC load memory does not match the length generated by the Siemens PLC basic program, so the basic program cannot map its interface onto the existing DB. This alarm is the first member of a whole family: alarms 400102 through 400177 follow the identical pattern for the standard interface DBs (DB2 to DB77), and on 840D sl the tool-management DBs 1000/1001 and 1071-1073 behave the same under 403000/403001/403071-403073. The control keeps running but the affected PLC/NCK data exchange is invalid until the mismatched block is removed.
Likely causes
- PLC user program was loaded with a basic-program version whose DB definitions differ from those already in the CPU
- Leftover or manually modified interface DB from an earlier software step
- Maximum PLC load-memory / program size exceeded so a DB was created truncated
Triage note: Series entry: identical definition applies to each documented number in 400102-400177 (and 403000/403001/403071-403073 on 840D sl) - text names the DB concerned. Official remedy: delete the displayed DB in STEP 7 and reload; valid for 840D/810D powerline and 840D sl.
Need the part urgently?
Send us alarm 400102 with your machine details — typical RFQ turnaround is 24–48h.