What causes Siemens SINUMERIK alarm 16678?

Part program contains an illegal or unsupported command for the current machine configuration. Channel or axis configuration does not support the programmed function. Required machine option not enabled for the commanded function. Axis assignment or transformation configuration error. Program execution sequence error.

How do I fix Siemens SINUMERIK alarm 16678?

1. Identify the program block that triggered the alarm — note the channel and block number. 2. Review the commanded function against the SINUMERIK programming manual. 3. Check if the required machine option is enabled for this function. 4. Verify axis assignments and transformation settings are correct for the application. 5. Consult the Siemens SINUMERIK alarm manual for alarm 16678 specific remedy.

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Siemens SINUMERIK Controller

Spindle · Intermediate · 30-120 minutes

Alarm 16678

Siemens 840D 16678 - Channel block following axis/spindle status impermissible

Alarm 16678 fires when a traversing command (G0/G1) is issued to a following axis or spindle while the generic coupling (CPOF) is active in an impermissible status. The NCK denies motion because the axis/spindle is synchronized to a master axis and cannot execute independent positioning in the current coupling state.

Siemens SINUMERIKSpindleIntermediate30-120 minutes

16678

Siemens 840D 16678 - Channel block following axis/spindle status impermissible

Channel block following axis/spindle status impermissible

Root Cause Summary

Alarm 16678 fires when a traversing command (G0/G1) is issued to a following axis or spindle while the generic coupling (CPOF) is active in an impermissible status. The NCK denies motion because the axis/spindle is synchronized to a master axis and cannot execute independent positioning in the current coupling state.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Review the NC program block sequence. Identify CPOF command preceding the traversing command. Verify CPOF N... or CPOF() syntax is correctly issued to establish coupling parameters (master axis, offset via MD32510 GENERIC_COUPLING_OFFSET, etc.).
2
Insert CPOF=0 (decouple) before any independent traversing of the following axis. Syntax: CPOF=0; G0 X100 (decouples following axis, permits motion). Check MD32500 GENERIC_COUPLING_TYPE and MD32502 GENERIC_COUPLING_MODE settings via Diagnostics > Parameters > Machine Data.
Decoupling interrupts synchronization; re-establish CPOF after positioning if synchronization must resume.
3
Verify axis/spindle status code (%4 in alarm). Cross-reference against NCK coupling state machine in SINUMERIK 840D documentation. Common impermissible states: coupling in transition, master axis in rapid traverse, or spindle orientation mode active.
4
Check MD32501 GENERIC_COUPLING_MASTER_AXIS to confirm the correct master axis is assigned. If following axis is incorrectly configured as master, the coupling status logic fails.

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