Code 231-B800: CC%2 safe inputs %1 not equal
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical CC%2 safe inputs %1 not equal 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] - A safety-related input of the CC is longer than 400 ms unequal to MC - Different levels at the safety module input: 4 = Acknowledgement of switch-off 8 = Safe reduced velocity of axes/spindle 10 = Safe reduced velocity of auxiliary axes 11 = Operating mode 3(detachable-key switch 1, Pos3) (safe controlled stop of axes/spindle) 18 = Operating mode 2 (detachable-key switch 1,Pos2) 19 = Operating mode 4 (detachable-key switch 2) - Wiring error X65, X66, (X67) – Safety module defective [Error correction] – Check the wiring X65, X66, (X67) – Exchange the safety module - Generate the service files and notify the Service Department [480] 10/2023
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-B800 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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