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Siemens SINUMERIK Controller
System · Intermediate · 10-20 minutes
Siemens 27020 - Axis stop E triggered
Alarm 27020 occurs when an axis actual position exceeds the configured Safe Limited Position (SLP) boundaries defined in the Safety Integrated parameters. This safety function violation triggers immediate axis stop and requires safety-acknowledged reset through the safety PLC or HMI before motion can resume.
27020
Siemens 27020 - Axis stop E triggered
Axis stop E triggered
This alarm is output together with alarms 27011 "Safe velocity exceeded" or 27012 "Safe limit position exceeded" (when configured as such in MD $MA_SAFE_VELO_STOP_MODE, $MA_SAFE_VELO_STOP_REACTION or MD: $MA_SAFE_POS_STOP_MODE) Control reaction: NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Trigger a LIFTFAST ASUB and internal activation of the safe operational stop (SBH) after expiry of the time set in MD $MA_SAFE_STOP_SWITCH_TIME_E.
Root Cause Summary
Alarm 27020 occurs when an axis actual position exceeds the configured Safe Limited Position (SLP) boundaries defined in the Safety Integrated parameters. This safety function violation triggers immediate axis stop and requires safety-acknowledged reset through the safety PLC or HMI before motion can resume.
Safety
- Safety Integrated alarm: work may only be carried out by qualified personnel. After any change to Safety Integrated settings or hardware, repeat the Safety Integrated acceptance test before returning the machine to service.
Causes and Fixes
- 1
Check Current Axis Position
Navigate to Diagnostics > Service > Axis States and verify actual position against configured SLP limits in Safety parameters.
Use machine coordinate system values, not workpiece coordinates when checking SLP boundaries
- 2
Verify SLP Parameter Settings
Access Safety Integrated > SLP Configuration and check SLP_POS_MIN/SLP_POS_MAX parameters for the affected axis.
SLP parameter changes require safety validation and may need TÜV certification
- 3
Perform Safety Reset
Execute safety-acknowledged reset via F-PLC or safety HMI, then manually jog axis back within SLP window before resuming automatic operation.
Call a technician if:
- ·SLP parameter modification required beyond operator authority
- ·Encoder feedback system malfunction
- ·Safety PLC programming changes needed
Prevention
- Regularly verify SLP window settings match operational requirements
- Include SLP status in pre-operation safety checklist
- Train operators on proper SLP activation/deactivation procedures
Common Mistakes
- Attempting motion reset without safety acknowledgment
- Modifying SLP parameters without proper safety validation
- Ignoring reference point validity before SLP operation
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