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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 27103 - Axis difference in function safe limit position , NCK: drive:
Alarm 27103 indicates a discrepancy between NCK (Numerical Control Kernel) and drive monitoring channels during safe limit position (SLP) cross-comparison in result list 1. This dual-channel monitoring mismatch compromises functional safety integrity and requires immediate diagnostic intervention to identify which channel has failed.
27103
Siemens 27103 - Axis difference in function safe limit position , NCK: drive:
Axis difference in function safe limit position, 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 limit position monitoring. - Safe limit position 1: Bit 2, 3 in result list 1 - Safe limit position 2: Bit 4, 5 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. Alarms.
Root Cause Summary
Alarm 27103 indicates a discrepancy between NCK (Numerical Control Kernel) and drive monitoring channels during safe limit position (SLP) cross-comparison in result list 1. This dual-channel monitoring mismatch compromises functional safety integrity and requires immediate diagnostic intervention to identify which channel has failed.
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
Access Diagnostics > Axis > [Axis %1] > Result List 1 in HMI/SINUMERIK Operate. Document the exact bit states for bits 2-5 on both NCK and DRIVE channels to confirm which is reporting OFF/failed state.
Do not clear alarms until root cause is identified; clearing may mask intermittent safety channel failures.
- 2
Verify drive encoder connection and signal integrity using Diagnostics > Drives > [Drive] > Encoder feedback. Check MD30110 (encoder type) and MD30111 (encoder resolution) parameters match hardware configuration.
Loss of encoder signal immediately disables safe limit monitoring on drive side.
- 3
Download and compare drive firmware version against your machine documentation. If discrepancy found, perform drive firmware update via STARTER software with power-down cycle.
Interrupt power during firmware update can corrupt safety module; use UPS-backed startup procedure.
- 4
If encoder and firmware are verified, perform hardware replacement of servo drive or safety relay module and re-initialize SLP parameters via MD32700-MD32799 range (safe limit position monitoring setup).
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