The Siemens Sinumerik 840D and 840D sl (solution line) are high-end CNCs; the 840D sl drives motion through the SINAMICS S120 system over DRIVE-CLiQ. Faults come from three areas — NC, PLC and the SINAMICS drive — and the alarm number tells you which. Below are the codes seen most often, with causes and fixes.
How Siemens 840D Alarm Numbers Are Grouped
- 0xx – 9xxx — NC / general alarms
- 2xxxx (25000, 25201) — Axis / channel alarms
- 4xxx (4060, 4065) — Machine-data / system messages
- 700xxx — PLC / machine-builder alarms
- F30xxx / F31xxx / F7xxx — SINAMICS S120 drive Faults (Axxxxx = warnings)
Common NC & System Alarms
| Alarm | Meaning | Common Cause & Fix |
|---|---|---|
| 4060 | Standard machine data loaded | Message after a data reset / first power-up. Load the correct machine archive. |
| 4065 | Buffered memory restored from backup | Battery-backed data lost and restored. Check the NC backup battery; reload data if needed. |
| 3000 | Emergency stop | E-stop active. Release the button, check the safety chain and PLC interlocks, reset. |
| 25000 | Axis hardware (encoder) fault | Measuring-system fault. Check encoder, cable and the DRIVE-CLiQ connection. |
| 25201 | Axis drive fault | A SINAMICS fault is active for this axis — read the F-code on the drive (below). |
| 700xxx | PLC / machine-builder alarm | Custom message (lube, air, hydraulics, doors). Clear the named condition. |
Common SINAMICS S120 Drive Faults (F-Codes)
| Code | Meaning | Common Cause & Fix |
|---|---|---|
| F30001 | Overcurrent | Motor short, ground fault or wrong drive/motor data. Megger motor & cables; check parameters. |
| F30002 | Overvoltage (DC link) | Regenerative / rapid-decel over-voltage or high line voltage. Check braking module and supply. |
| F30003 | Undervoltage (DC link) | Supply loss, blown fuse or infeed/contactor fault. Check the line supply and infeed module. |
| F30004 | Inverter overtemperature | Cooling fan failure or blocked heatsink. Clean/replace the fan; check ambient temperature. |
| F30005 | Inverter I²t overload | Continuous overload. Reduce cutting load; check mechanical friction/bind. |
| F30011 | Line phase failure (main circuit) | Missing input phase. Check 3-phase supply, fuses and contactor. |
| F30015 | Motor cable phase failure | Open/loose motor power lead. Check the motor cable and terminals. |
| F30021 | Ground fault | Insulation breakdown in motor or cable. Megger-test and repair/replace. |
| F31xxx | Encoder fault (e.g. F31100 / F31110) | Measuring-system fault. Check encoder, cable and DRIVE-CLiQ link. |
| F7011 | Motor overtemperature | Overload, blocked motor cooling or faulty motor temperature sensor. |
First Steps When an 840D Alarms
- Note the alarm number and full text — it states the area (NC / PLC / drive).
- For 25201 / F-codes, open drive diagnosis to read the exact SINAMICS fault and the affected component (via DRIVE-CLiQ topology).
- Check the infeed/line supply, DC link voltage, cooling fans and encoder/DRIVE-CLiQ wiring.
- For overcurrent / ground-fault codes, megger the motor and cables before refitting a module.
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Quick-reference of common alarms. For the complete list, refer to the Siemens Sinumerik 840D sl Diagnostics Manual.