What causes Siemens SINUMERIK alarm 10261?

The internal communication between the NCK modules that evaluate the channel-specific VDI signals (START/STOP/ RESET/DDTG/ASUBS/...) and the block preparation are overloaded.. The block preparation modules are not being allocated enough computing time.

How do I fix Siemens SINUMERIK alarm 10261?

1. More processor time must be allocated to the block preparation modules. 2. Machine data $MN_IPO_SYSCLOCK_TIME_RATIO or $MN_SYSCLOCK_CYCLE_TIME can be increased for this purpose. 3. Switch control OFF - ON

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Siemens SINUMERIK Controller

Communication · Intermediate · 30-120 minutes

Alarm 10261

Siemens 10261 - Communication overload for block preparation

Alarm 10261 indicates the NCK (Numerical Control Kernel) block preparation process cannot keep pace with the programmed feed rate due to communication bottlenecks between the HMI and NCK. This typically occurs when the part program contains excessive small block segments, complex transformations, or high-frequency communication commands that exceed the control's processing capacity for lookahead calculation.

Siemens SINUMERIKCommunicationIntermediate30-120 minutes

10261

Siemens 10261 - Communication overload for block preparation

Communication overload for block preparation

Root Cause Summary

Alarm 10261 indicates the NCK (Numerical Control Kernel) block preparation process cannot keep pace with the programmed feed rate due to communication bottlenecks between the HMI and NCK. This typically occurs when the part program contains excessive small block segments, complex transformations, or high-frequency communication commands that exceed the control's processing capacity for lookahead calculation.

Safety

Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.

Causes and Fixes

1
Review the NC program around the alarm occurrence point. Check for sequences with hundreds of consecutive blocks shorter than 0.1mm using the program editor's block length analysis.
2
Enable COMPRESSOR function (G450/COMPON or COMPCURV/COMPCAD) in the program header to consolidate microblocks. Verify machine data MD20200 $MC_COMPRESSOR_MODE allows compression.
Test COMPRESSOR settings on simple geometry first - incorrect parameters can alter tool path contour accuracy.
3
Increase CAM post-processor tolerance settings (linear/chord tolerance) to generate larger block segments, typically 0.01-0.05mm for finishing operations.
4
Verify channel machine data MD28360 $MC_MM_IPO_BUFFER_SIZE is set to maximum allowable value (typically 300-500) to increase block buffer depth for lookahead.

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