Code 4170: Invalid M function number for channel synchronisation assigned
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical Invalid M function number for channel synchronisation assigned 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
Definitions: An M number between 0 and 99 has been specified In machine data MD10800 $MN_EXTERN_CHAN_SYNC_M_NO_MIN or MD10802 $MN_EXTERN_CHAN_SYNC_M_NO_MAX for the configuration of the M number range for channel synchronization in ISO2/3 mode or the machine data MD10802 $MN_EXTERN_CHAN_SYNC_M_NO_MAX is smaller than MD10800 $MN_EXTERN_CHAN_SYNC_M_NO_MIN. Reaction: Mode group not ready. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Remedy: Check MD10800 $MN_EXTERN_CHAN_SYNC_M_NO_MIN and MD10802 $MN_EXTERN_CHAN_SYNC_M_NO_MAX. Program Continuation: Switch control OFF - ON.
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 4170 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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