Siemens alarm 428604: Failure of a DP slave
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
The PROFIBUS-DP diagnostics OBs (OB82 diagnostic interrupt / OB86 station failure) were triggered because a DP slave stopped answering on the I/O bus. All field signals routed through that slave are lost, so interlocks depending on them typically force a stop or inhibit starts. Identify the failed station from the alarm/bus diagnostics, then repair bus wiring, supply or the slave module itself.
Likely causes
- DP slave powered down or its 24 V supply failed
- Bus cable/connectors to the slave interrupted or unterminated
- Slave electronics defective (IM/ET200-style head module)
- Configuration mismatch after replacing the slave with different article
Triage note: Member of the 4286xx I/O diagnostics family (428601-428634), all raised via OB82/OB86 with remedy 'rectify the cause of the error displayed'. 428623/428624 name the bus/slave numbers.
Need the part urgently?
Send us alarm 428604 with your machine details — typical RFQ turnaround is 24–48h.