Code 231-8BA0: Incorrect reference signal or line count %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Incorrect reference signal or line count %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] - Incorrect entry for the line count under STR in the motor table - Faulty reference signal - Noise signals - Motor encoder cable defective (break or short circuit) - Scale or scale tape contaminated or defective - Scanning head contaminated or defective - Signal cable defective - Encoder input defective on the control - Penetration of humidity [Error correction] - Inform your service agency - Check the entry in the motor table - Check the signals of the speed encoder (PWM 8) - Check the encoder cable for breaks or short circuits under mechanical load (folding, stretching, etc.) - Check the shield and its connection in the encoder cable - Exchange the encoder cable - Exchange the motor
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 231-8BA0 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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