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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 840D 27022 - Axis stop C triggered
Alarm 27022 is a secondary alarm triggered when axis safety functions detect a fault condition (Safe Velocity Exceeded or Safe Position Limit Exceeded) and the configured stop reaction is set to 'Stop C' (monitored stop). This alarm indicates the safety-monitored deceleration to standstill was initiated, but the axis did not achieve safe velocity compliance within the monitored parameters defined in $MA_SAFE_VELO_STOP_MODE or $MA_SAFE_POS_STOP_MODE.
27022
Siemens 840D 27022 - Axis stop C triggered
Axis stop C triggered
Siemens SINUMERIK alarm 27022: Axis stop C triggered. This alarm indicates a fault or error condition on the SINUMERIK 840D control. Refer to the Siemens SINUMERIK alarm documentation for the complete description and remedy.
Root Cause Summary
Alarm 27022 is a secondary alarm triggered when axis safety functions detect a fault condition (Safe Velocity Exceeded or Safe Position Limit Exceeded) and the configured stop reaction is set to 'Stop C' (monitored stop). This alarm indicates the safety-monitored deceleration to standstill was initiated, but the axis did not achieve safe velocity compliance within the monitored parameters defined in $MA_SAFE_VELO_STOP_MODE or $MA_SAFE_POS_STOP_MODE.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Check NCK parameters: Display $MA_SAFE_VELO (safe velocity threshold) and $MA_SAFE_VELO_STOP_REACTION (should be 2 or 3 for Stop C). Navigate to Diagnostics > Parameters > Machine Data > Safety Functions.
- 2
Verify MD 32310 (MAX_AX_ACCEL) and MD 32300 (MAX_AX_VELO) are correctly set for the axis. Ensure deceleration ramp is sufficient to bring axis below safe velocity threshold within $MA_SAFE_VELO_STOP_TIME_LIMIT (typically 50-500ms).
Increasing MAX_AX_ACCEL beyond mechanical limits can cause servo instability. Consult machine tool documentation.
- 3
In Siemens HMI, navigate to Diagnostics > Alarms > Alarm log and check the preceding alarm (27011 'Safe velocity exceeded'). This confirms the root fault condition.
- 4
Clear alarm history and perform a controlled axis jog at reduced feedrate (10-25% of MAX_AX_VELO) to confirm axis responds to Stop C deceleration without oscillation or overshoot.
Perform this test in Manual mode with Machine Ready disabled until issue is confirmed resolved.
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