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Siemens SINUMERIK Controller
System · Intermediate · 30-120 minutes
Siemens 840D 20093 - Axis standstill monitoring at fixed-stop end point has been triggered
Alarm 20093 indicates that an axis has failed to achieve zero speed (standstill) within the configured monitoring window after a fixed-stop end point selection was completed. This occurs when the axis velocity remains above the zero speed threshold defined in MD21080 (VELO_LIMIT_STANDSTILL) for an extended period, typically due to servo lag, mechanical binding, or incorrect positioning parameters.
20093
Siemens 840D 20093 - Axis standstill monitoring at fixed-stop end point has been triggered
Axis standstill monitoring at fixed-stop end point has been triggered
Siemens SINUMERIK 840D alarm 20093: Axis standstill monitoring at fixed-stop end point has been triggered. This alarm indicates a program or channel-level error on the SINUMERIK control. The part program or machine function cannot be executed as commanded.
Root Cause Summary
Alarm 20093 indicates that an axis has failed to achieve zero speed (standstill) within the configured monitoring window after a fixed-stop end point selection was completed. This occurs when the axis velocity remains above the zero speed threshold defined in MD21080 (VELO_LIMIT_STANDSTILL) for an extended period, typically due to servo lag, mechanical binding, or incorrect positioning parameters.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access Diagnostics > Axis > Actual Values in HMI to verify real-time axis velocity (VELO_ACT) is truly non-zero or oscillating around the zero-speed threshold during fixed-stop positioning.
- 2
In NCK Parameter menu, navigate to Machine Data MD21080 (VELO_LIMIT_STANDSTILL) and verify the standstill velocity threshold. Typical values are 0.1-1.0 mm/min depending on axis type. Increase threshold by 10-20% and test fixed-stop selection.
Do not increase threshold excessively; this reduces positioning accuracy.
- 3
Check MD21084 (TIME_LIMIT_STANDSTILL) - this sets the maximum time the axis has to achieve standstill. If value is too low (typically 100-500ms), increase to 500-1000ms and retest.
- 4
Perform axis tuning via Diagnostics > Service > Axis Optimization or manually adjust MD32300 (GAIN_PROP_VOLT) and MD32310 (GAIN_INTEGR_VOLT) servo loop gains to improve settling behavior.
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