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Access Diagnostics > Parameters > Machine Data (MD) and navigate to MD21180 (SafetyPlaneDistance) or check SD33150 in the Safety Data set. Verify the value is positive and expressed in the active unit (mm or inch).

Do not attempt to set SafetyPlaneDistance to zero; minimum recommended value is 2-5mm depending on tool geometry.

If the parameter appears correct in diagnostics, check the active G-code block (Block %2 in alarm) for embedded safety distance definitions via G65/G66 macros or SUPTOOL commands that may override the machine parameter.

Reload the machine parameter set via NCK > Parameter > Load/Reload to ensure the displayed value matches flash memory. If the value still reads zero or negative, reinitialize MD21180 to the default positive value from the machine's parameter backup (*.spf file).

After correcting the parameter, clear the alarm by pressing Reset and re-execute the program block. Verify the safety plane distance is now positive in the subsequent block preparation.

Review the active part program and macro subroutines triggered at Block %2 (noted in alarm message). Search for SUPTOOL, ATRAN, or G65 macro calls that reference safety distance arguments (typically P-word or R-word parameters).

Block numbers in alarms reference the NCK's internal block counter, not the part program line numbers; use the Trace function (Diagnostics > Program > Trace) to correlate to the source.

Inspect the tool changer subroutine (typically M6 logic in the PLC) or the automatic cycle macro (/AUTOMATIC/*.spf files) for any arithmetic operations or variable assignments that calculate safety distance as (CurrentZ - NextZ) or similar expressions that may yield zero or negative results.

Modify the offending macro or M-function to ensure all safety distance calculations include a positive offset guard: IF SafetyDist <= 0 THEN SafetyDist = MD21180. Reload the macro via NCK > Subroutines > Reload.

Re-execute the part program from Block %2 and confirm the alarm clears. If the alarm persists, enable NCK Trace (Diagnostics > Program Trace) to log the exact parameter values passed to the safety plane logic.

Access Diagnostics > Offsets > Tool Offset and Workpiece Offset. Verify all active tool offset values (D register, typically D1) are positive. Check that G43 (or G44 if used) is correctly applying tool length in the Z-axis direction.

Negative tool offsets are valid for tool path calculations but will reduce the effective safety plane height when combined with SafetyPlaneDistance; ensure the sum remains positive.

Confirm the Workpiece Offset (via G92, G54~G59 work offset tables) in the Z-axis is not excessively negative. Calculate: EffectiveSafetyPlane = MD21180 + WorkOffsetZ + ToolOffsetZ. This value must be greater than zero.