Siemens alarm 400274: Direct keys 1 failed
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
The direct key module on input 1 (machine-function keys wired directly to the NCK/PLC keypad interface) missed its internal timeout, i.e. its cyclic response disappeared. The affected direct keys stop working until communication recovers. Check the connection to the direct key module per the official remedy.
Likely causes
- Direct key module disconnected or cable fault
- Module supply voltage missing
- Internal timeout value too tight
- Module hardware defect
Triage note: Group context: 400271/400272 (communication errors, internal error code), 400275 (direct keys 2 failed) and 400276/400277 (pointer parameters) cover the rest of the direct-key diagnostics.
Need the part urgently?
Send us alarm 400274 with your machine details — typical RFQ turnaround is 24–48h.