Siemens alarm 26101: Axis %1 drive %2 communication failure
SINUMERIK 840D sl drive communication alarm (PROFIdrive) · Siemens 840D/810D powerline
What it means
The drive is not communicating over PROFIdrive (isochronous connection broken).
Likely causes
- bus connector removed/loose or option module inactive
- bus configuration mismatch (topology change)
- failed transceiver in drive module or NCU/CCU port
- EMC-induced telegram errors (shielding)
Triage note: Check bus configuration and interface seating first; verify terminator at last node.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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6XV1830-3GH50-… / RJ45-M12 industrial PROFINET cables
PROFIBUS/PROFINET bus cable · Primary suspect
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6SL3120-… / 6SL3210-…
SINAMICS motor/line module comms port failure · Common cause
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6SL3040-… (CU/NCU 71x.x)
control unit bus port · Check if others ruled out
Need the part urgently?
Send us alarm 26101 with your machine details — typical RFQ turnaround is 24–48h.