Code 231-A930: Safely limited speed (SLS) exceeded %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Safely limited speed (SLS) exceeded %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] - SKERN-CC detected an impermissibly fast axis movement above the safe reduced speed. (SLS2,SLS3,SLS4) Possible causes: - Guard door was opened (at high speed) during an axis movement. - Machine parameter for reduced speed is defined too small. [Error correction] - Check whether the guard door was opened during an axis movement. - SLS2: Check the entry in machine parameter "speedLimitSom2." - SLS3: Check the entry in machine parameter "speedLimitSom3." - SLS4: Check the entry in machine parameter "speedLimitSom4." - 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-A930 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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