Code 231-E220: Standstill monitoring SKERN-CC %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Standstill monitoring SKERN-CC %1 alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
[Cause of error] - SKERN-CC detected an impermissibly large axis movement in the SOS safety condition. The standstill speed, however, was not exceeded. The maximum permissible path is defined in the machine parameter MP positionRangeVmin. Possible causes: - Machine parameter "positionRangeVmin" is defined too small. - The brake was deactivated before the position controller was closed. - The brake was not activated before the position controller was opened. - When an axis was switched on, some existing following error was corrected. - The brake is defective. - There was an attempt to move an axis in the SOS condition (PLC?) [Error correction] - Check the entry in machine parameter positionRangeVmin. - Check the sequence of deactivating the brake and closing the position controller. - Check the sequence of activating the brake and opening the position controller. - Check whether there is a following error after an axis is locked. - Inform your service agency.
Source: HEIDENHAIN NC Error Messages — TNC7/640/620/320/128, CNC PILOT 640, MANUALplus 620 (10/2023)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Heidenhain TNC Series CNC Alarms
Heidenhain controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 231-E220 on the TNC Series CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Heidenhain's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4497 Heidenhain TNC Series CNC codes.
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