Code 231-93B0: PDT1 feedforward current contrlr.: Invalid cutoff freq.
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical PDT1 feedforward current contrlr.: Invalid cutoff freq. 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] - Illegal maximum cutoff frequency in machine parameter "iCtrlDiffFreqFF." - The following are the maximum permissible cutoff frequencies for the respective PWM frequencies: PWM frequency Maximum cutoff frequency 3333 Hz 800 Hz 4000 Hz 960 Hz 5000 Hz 1200 Hz 6666 Hz 1600 Hz 8000 Hz 1920 Hz 10000 Hz 2400 Hz [Error correction] - Enter the permissible cutoff frequency in machine parameter "iCtrlDiffFreqFF." - 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 231-93B0 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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