Code 16746: [Channel %1: ] Block %2 spindle %3 selected gear stage %4 not installed
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 spindle %3 selected gear stage %4 not installed 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 = Spindle number %4 = Gear stage Definitions: The first gear stage data block is active. The requ ired gear stage is not installed in the 1st gear stage data block. The number of gear stages installed is configured in MD35090 $MA_NUM_GEAR_STEPS. Examples of the occurrence of the alarm with 3 three gear stages installed (MD 35090 $MA_NUM_GEAR_STEPS = 3): *... M44 or M45 has been programmed for the spindle concerned *...M70 has been programmed and MD35014 $MA_GEAR_STEP_USED_IN_AXISMODE is larger than 3. Reaction: Correction block is reorganized. Interface signals are set. Alarm display. Remedy: Modify part program: Only those valid gear stages can be entered which have also been installed according to MD35090 $MA_NUM_GEAR_STEPS. Limit M70 configuration (MD 35014 $MA_GEAR_STEP_USED_IN_AXISMODE) to MD35090 $MA_NUM_GEAR_STEPS. Program Continuation: Clear alarm with NC ST ART or RESET key and continue the program. Diagnostics Manual (DAsl), 03/2009
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 16746 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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