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Siemens SINUMERIK Controller
Spindle · Intermediate · 30-120 minutes
Siemens 840D 16691 - Channel block following axis/spindle changing the reference
Alarm 16691 occurs when an NC program attempts to execute a reference system change (via SETZERO, G92, or similar commands) on a spindle axis while generic coupling is active. Generic coupling creates a kinematic relationship between axes that prevents independent reference modifications, as the coupled slave axis reference is dependent on the master axis position.
16691
Siemens 840D 16691 - Channel block following axis/spindle changing the reference
Channel block following axis/spindle changing the reference
Siemens SINUMERIK 840D alarm 16691: Channel block following axis/spindle changing the reference. This alarm indicates a program or channel-level error on the SINUMERIK control. The part program or machine function cannot be executed as commanded.
Root Cause Summary
Alarm 16691 occurs when an NC program attempts to execute a reference system change (via SETZERO, G92, or similar commands) on a spindle axis while generic coupling is active. Generic coupling creates a kinematic relationship between axes that prevents independent reference modifications, as the coupled slave axis reference is dependent on the master axis position.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Check NC program block %2 for SETZERO, G92, or equivalent reference change commands targeting axis/spindle %3 using the Program Editor (Cycle→Program→Edit).
- 2
Verify generic coupling status via Diagnostics→Machine Data→Spindle Parameters, check MD10070 (GENERIC_COUPLING_TYPE) value. Non-zero value indicates active coupling.
Do not modify machine data during program execution.
- 3
In the NC program, decouple the axis before reference change using COUPLE(axis, 0) or equivalent decoupling command, then execute SETZERO, then re-engage coupling.
Ensure mechanical load is stable before decoupling to prevent axis drift.
- 4
Test corrected program in DRY RUN mode (operating mode: JOG or TEST) before resuming automatic cycle.
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