Code 231-A005: CC%2 Warning: Controller unit not suited for FS
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical CC%2 Warning: Controller unit not suited for FS 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] When checking the safety kernel software SKERN-CC, the control unit detected, that this hardware (CC, UEC, UMC) is not suitable for control systems with functional safety (FS). This controller unit fulfills the safety requirements according to EN 13849 and is not approved for functional safety. [Error correction] - Exchange the affected controller unit (CC, UEC, UMC) - 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-A005 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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