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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 27106 - Axis difference in function safe velocity nx, NCK: drive:
Alarm 27106 indicates a mismatch between NCK and drive monitoring channels during cross-comparison of Safe Torque Off (STO) function monitoring, specifically in the safe velocity monitoring bits (16-19) of result list 2. This dual-channel discrepancy suggests either a communication integrity issue between NCK and drive, a parameter mismatch in safe velocity threshold settings, or a drive-side monitoring failure in the SINAMICS servo controller.
27106
Siemens 27106 - Axis difference in function safe velocity nx, NCK: drive:
Axis difference in function safe velocity nx, NCK: drive
During cross-comparison of result list 2 a difference was detected between the NCK and drive monitoring channels in the status of safe velocity monitoring. - Safe velocity nx+: Bit 16, 17 in result list 2 - Safe velocity nx-: Bit 18, 19 in result list 2 Monitoring status (,): - OFF = Monitoring is inactive in this monitoring channel - OK = Monitoring is active in this monitoring channel, limit values are not violated - L+ = Monitoring is active in this monitoring channel, upper limit exceeded - L- = Monitoring is active in this monitoring channel, lower limit exceeded Control reaction: NC Start disable in this channel. Alarm display. A Stop F was triggered. If safe monitoring was active, STOP B was also triggered automatically. In this case, a power OFF/ON of the control will be required.
Root Cause Summary
Alarm 27106 indicates a mismatch between NCK and drive monitoring channels during cross-comparison of Safe Torque Off (STO) function monitoring, specifically in the safe velocity monitoring bits (16-19) of result list 2. This dual-channel discrepancy suggests either a communication integrity issue between NCK and drive, a parameter mismatch in safe velocity threshold settings, or a drive-side monitoring failure in the SINAMICS servo controller.
Safety
- Drive/power/encoder circuit: hazardous voltages may remain in the DC link after power-off. Lock out / tag out, wait for discharge per the drive documentation, and use qualified personnel only.
Causes and Fixes
- 1
Navigate to Diagnostics > Parameters > Machine Data (MD) and verify MD 32100 (Enable Safe Velocity Monitoring) and MD 32110 (Safe Velocity Threshold nx+) are correctly set on NCK side.
Document current values before modification.
- 2
Access the SINAMICS servo drive parameter menu (Startup > Drive > Parameters) and cross-check the corresponding safe velocity threshold parameters against NCK settings. Ensure P0640 (Rated Motor Voltage) and velocity-related safety parameters are synchronized.
Parameter changes on active servo drives require commissioning lock disengagement.
- 3
Perform a full parameter transfer from NCK to drive using PLC menu: System > Service > Parameter Transfer or manual resynchronization via HMI to restore coherence between channels.
- 4
Execute a warm restart (cycle power off/on) to reinitialize the cross-comparison monitoring in result list 2 and confirm alarm clears.
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