What causes Siemens SINUMERIK alarm 20120?

Part program contains an illegal or unsupported command for the current machine configuration. Channel or axis configuration does not support the programmed function. Required machine option not enabled for the commanded function. Axis assignment or transformation configuration error. Program execution sequence error.

How do I fix Siemens SINUMERIK alarm 20120?

1. Identify the program block that triggered the alarm — note the channel and block number. 2. Review the commanded function against the SINUMERIK programming manual. 3. Check if the required machine option is enabled for this function. 4. Verify axis assignments and transformation settings are correct for the application. 5. Consult the Siemens SINUMERIK alarm manual for alarm 20120 specific remedy.

axismd.ai

Siemens SINUMERIK Controller

System · Intermediate · 30-120 minutes

Alarm 20120

Siemens 840D 20120 - Axis: too many compensation relations

Alarm 20120 fires when the number of interpolatory compensation relations (Lagrange interpolation tables) configured for a single axis exceeds the total number of axes defined in the machine tool system. The NCK automatically disables compensatory interpolation on the affected axis to prevent system instability.

Siemens SINUMERIKSystemIntermediate30-120 minutes

20120

Siemens 840D 20120 - Axis: too many compensation relations

Axis: too many compensation relations

Root Cause Summary

Alarm 20120 fires when the number of interpolatory compensation relations (Lagrange interpolation tables) configured for a single axis exceeds the total number of axes defined in the machine tool system. The NCK automatically disables compensatory interpolation on the affected axis to prevent system instability.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Access Diagnostics > Parameters > Machine Data > Compensation menu in SINUMERIK HMI or via NCK parameter interface.
2
Compare current value of MD10710 (or MD10712 if axis-specific) against MD20050 (total number of axes). Document the discrepancy.
3
Reduce compensation relation count to equal or less than MD20050 value. If 5 axes are configured, limit compensation relations to ≤5 per axis.
Verify with process engineering that reduced compensation granularity meets accuracy requirements before deployment.
4
Perform NCK initialization (warm reset via HMI or OEM reset procedure) to reload machine data. Verify alarm 20120 is cleared in Diagnostics > Alarms.

Service Recommended confidence

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

Always verify with your machine manual or a certified technician before performing service procedures.