Siemens alarm 26020: Axis %1 encoder %2 hardware fault %3 during encoder initialization
SINUMERIK axis alarm (encoder hardware, 611D) · SIMODRIVE 611D/611U
What it means
Initialization of the absolute encoder failed; fine coding identifies interface problem (e.g. SSI level on data line, no encoder connected, incorrect cable, encoder faulty - bit 15).
Likely causes
- encoder electronic failure (bit 15)
- incorrect encoder cable / SSI level detected on EnDat data line (bit 11)
- control board not supporting the encoder interface (EnDat/SSI)
Triage note: Evaluate error fine coding (%3) against absolute-encoder interface diagnostics table.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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EQN1325 / ERN1387 / absolute encoder per axis
absolute encoder · Primary suspect
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6FX5002-2E…
encoder cable · Common cause
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6SN1118-…
611D control board supporting EnDat/SSI · Check if others ruled out
Need the part urgently?
Send us alarm 26020 with your machine details — typical RFQ turnaround is 24–48h.