Code 10866: [Channel %1: ] Block %2 FZ is active, but the number of teeth of the active D number %4 of tool %3 is zero.
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 FZ is active, but the number of teeth of the active D number %4 of tool %3 is zero. 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
Parameters: %1 = Channel number %2 = Block number, label %3 = Identifier %4 = D number Definitions: Tooth feedrate is active for the displayed traver sing block, but a D number of 0 is selected with $TC_DPNT (number of teeth). Traversing can be performed after acknowledgement of the error. For calculation of the effective feedrate one tooth per revolution is assumed. Reaction: Correction block is reorganized. Local alarm reaction. Interface signals are set. Alarm display. NC Stop on alarm. Remedy: Check the NC program for correct tool selection and correct it, if required; then continue the NC program with NC start. Or: Continue the NC program with NC start. The feedrate will be calculated assuming 1 tooth. Program Continuation: Clear alarm with NC ST ART or RESET key and continue the program.
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 10866 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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