Siemens alarm 400260: Failure of machine control panel 1
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
Machine control panel interface 1 stopped delivering its cyclic telegram: the FB1 monitoring timer MCP1Timeout expired, the panel address in DB7 (MCP1BusAdr) is wrong, or sending was disabled via DB7 bit MCP1NotSend=TRUE. The PLC loses keys, switches and mode selection from that panel while the alarm is standing. Wiring, PROFIBUS address and the FB1/DB7 configuration must be checked before restart.
Likely causes
- MCP cable broken/disconnected or PROFIBUS drop faulted
- Wrong MCP1BusAdr in DB7 versus DIP-switch address on the panel
- MCP1NotSend set TRUE in DB7
- FB1 MCP1Timeout too short or MCP1Cycl altered from default
- Defective MCP electronics
Triage note: Alarm 400261 reports the identical failure for a second machine control panel (interface 2).
Need the part urgently?
Send us alarm 400260 with your machine details — typical RFQ turnaround is 24–48h.