Code 16946: [Channel %1: ] Start via START is not allowed
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Start via START is not allowed 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 ID Definitions: This alarm is active with "Group Serupro" only. "Group Serupro" is activated by means of MD10708 $MN_SERUPRO_MASK, Bit 2 and enables the retrac e support of entire channel groups during block search. The MD22622 $MC_DISABLE_PLC_START specifies wh ich channel is generally started from the PLC and which channel is only allowed to be star ted from another channel via the START part program command. This alarm occurs if the channel was started via the START part programm command and MD22622 $MC_DISABLE_PLC_START==FALSE was set. Reaction: Alarm display. Remedy: Modify MD22622 $MC_DISABLE_PLC_START of sw itch off "Group Serupro" (see MD10708 $MN_SERUPRO_MASK). Program Continuation: Clear alarm with the Delete key or NC START.
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 16946 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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