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Siemens SINUMERIK Controller
Program/G-code · Intermediate · 30-120 minutes
Siemens 16687 - Block motion synchronous action type of coupling/instruction
Alarm 16687 occurs when an NC block attempts to execute a spindle command (such as SPINDL, M3/M4, or speed override) on a spindle axis that is configured as a generic coupling type incompatible with that instruction. The generic coupling configuration (MD 37100 GENERIC_COUPLING_TYPE) restricts which spindle operations are permitted for the coupled axis.
16687
Siemens 16687 - Block motion synchronous action type of coupling/instruction
Block motion synchronous action type of coupling/instruction
The stated instruction is not permitted for the stated type of generic coupling Control reaction: NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
Alarm 16687 occurs when an NC block attempts to execute a spindle command (such as SPINDL, M3/M4, or speed override) on a spindle axis that is configured as a generic coupling type incompatible with that instruction. The generic coupling configuration (MD 37100 GENERIC_COUPLING_TYPE) restricts which spindle operations are permitted for the coupled axis.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Navigate to Diagnostics > Parameters > Machine Data > Spindle group and locate MD 37100 GENERIC_COUPLING_TYPE for the spindle axis shown in alarm parameter %3.
- 2
Verify the coupling type: Type 1 (speed-coupled) permits SPINDL/M3/M4 commands; Types 2-4 (position, synchronous, electronic cam) restrict direct speed commands and require COUPLE/UNCOUPLE syntax.
Do not change MD 37100 without understanding the mechanical coupling design intent.
- 3
Cross-reference the NC program block %2 with the spindle command syntax. If using SPINDL S=... on a type 2-4 coupling, modify to use COUPLE command instead, or request spindle reconfiguration from process engineering.
- 4
Clear the alarm (NC Stop + Reset) after correcting the NC program or MD configuration, then verify with a dry run (DRY RUN mode in NCK menu).
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