Siemens alarm F07900: Drive: motor blocked
SINAMICS drive fault (motion/monitoring) · SINAMICS S120
What it means
Speed controller sat at torque limit longer than p2177 while speed stayed below p2175 threshold - commanded rotation not happening.
Likely causes
- mechanically blocked axis (crash, jammed ballscrew, brake still applied)
- failed axis holding brake not opening
- swapped motor phases / encoder direction mismatch
- undersized drive hitting current limits
- encoder feedback failure making drive think motor is stalled
Triage note: First verify shaft turns freely by hand with power off and listen/measure for brake release click; do not chase electronics first.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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axis brake (per motor/axis build)
holding brake / brake rectifier · Primary suspect
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encoder per axis
encoder (false stall detection) · Common cause
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ballscrew/bearing/gib components
axis mechanics (jam) · Common cause
Need the part urgently?
Send us alarm F07900 with your machine details — typical RFQ turnaround is 24–48h.