Code 231-E250: Error in cut-out channel %1 Ch:%4 St:%5 St-2ndCh:%6
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Error in cut-out channel %1 Ch:%4 St:%5 St-2ndCh:%6 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
Sgn:%7 [Cause of error] An error occurred in the self-test for safety. The cut-out channel test detected a fault. Key to abbreviations: Ch (cut-out channel concerned): 1: STO.A.x 2: STO.B.x 3: STO.A.G 4: STOS.A.G St (actual condition of the cut-out channel): 0: Cut-out channel is inactive, although it is supposed to be active 1: Cut-out channel is active, although it is supposed to be inactive St-2ndCh (actual condition of the second cut-out channel): 0: Cut-out channel is inactive 1: Cut-out channel is active The second cutout channel is STO.A.x if Ch=2, and STO.B.x if Ch=1, Ch=3 and Ch=4 Sgn (cut-out signal concerned): 0: STOS.A.MC 1: STO.A.MC.WD 2: STO.A.P.x 3: STO.A.PIC 4: STO.B.CC.WD 5: STO.B.P.x 9: STO.A.T 99: no cut-out signal [Error correction] - Check the wiring (PWM cable) - Replace the defective hardware (power module, controller unit) - 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-E250 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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