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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 27102 - Axis difference in function safe velocity , NCK: drive:
Alarm 27102 indicates a discrepancy between NCK (Numerical Control Kernel) and drive safety monitoring channels during cross-comparison of result list 1, specifically in the safe velocity monitoring bits. This dual-channel monitoring mismatch suggests either a communication failure between NCK and drive, parametric inconsistency, or hardware degradation in the safety chain.
27102
Siemens 27102 - Axis difference in function safe velocity , NCK: drive:
Axis difference in function safe velocity, NCK: drive
During cross-comparison of result list 1 a difference was detected between the NCK and drive monitoring channels in the status of safe velocity monitoring. - Safe velocity 1: Bit 6, 7 in result list 1 - Safe velocity 2: Bit 8, 9 in result list 1 - Safe velocity 3: Bit 10, 11 in result list 1 - Safe velocity 4: Bit 12, 13 in result list 1 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 27102 indicates a discrepancy between NCK (Numerical Control Kernel) and drive safety monitoring channels during cross-comparison of result list 1, specifically in the safe velocity monitoring bits. This dual-channel monitoring mismatch suggests either a communication failure between NCK and drive, parametric inconsistency, or hardware degradation in the safety chain.
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
Verify physical integrity of communication cables between NCK control unit and drive (servo amp). Check PROFIBUS/PROFINET connectors for corrosion, loose pins, or damage. Inspect shielding and proper grounding at both ends.
Power down machine before inspecting connectors.
- 2
In NCK diagnostics menu, navigate to Diagnosis > Communication > PROFIBUS/PROFINET and verify sync time and telegram error counters. Reset counters and run a test cycle; if errors reappear, suspect cabling or interface module fault.
- 3
Check parameter MD 31010 (SafetyInterfaceType) and MD 32110 (SafetyMonitoringMode) to confirm drive safety interface is properly configured. Cross-reference drive type documentation to ensure matching protocol version.
- 4
If errors persist, replace communication interface module or drive safety card and re-establish NCK-drive handshake by performing a Safety Init cycle (typically accessed via HMI or parameter reset).
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