Code 231-9510: PWM frequency change during active servo control %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical PWM frequency change during active servo control %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] - The PWM frequency in machine parameter ampPwmFreq must not be changed while the drive or a corresponding drive is still in a control loop. Corresponding axis: X51 - X52 X53 - X54 X55 - X56 X57 - X58 X80 - X81 X82 - X83 X84 - X85 [Error correction] - Deactivate the drive controller before changing machine parameter ampPwmFreq - 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 231-9510 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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