Code 207424: <location>Drive: Operating condition for APC not valid
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Drive: Operating condition for APC not valid 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
Message value: Fault cause: %1 bin Drive object: SERVO Reaction: NONE Acknowledge: NONE Cause: The APC function (Advanced Positioning Contro l) has identified an invalid operating condition. Alarm value (r2124, interpret hexadecimal): Bit 0 = 1: APC is operating without encoder Bit 1 = 1: The load measuring system for APC, selected usi ng p3701, has a fault. The APC function is disabled. Bit 2 = 1: The load measuring system for APC, selected usin g p3701, has a fault. The pulse de-coupling is disabled, i.e. the speed of the motor measuring system is used as speed for the closed-loop motor speed control. Remedy: Re bit 0: Only use the APC function in operation with an encoder. Re Bit 1, 2: Check the load measuring system.
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 207424 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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