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Navigate to SYSTEM > PARAM and access parameter 1815. Check if bit 0 (REF) is set to 1, which enables reference position setting mode.

If reference point adjustment is complete, set parameter 1815 bit 0 to 0 while in parameter write-enable mode (parameter 0000 bit 0 = 1 or key switch in EDIT/WE position).

Ensure reference point has been properly established before disabling this mode, otherwise machine zero position will be lost

Cycle power to the CNC system completely (turn OFF and back ON) to exit reference position adjustment mode and clear the alarm.

After power cycle, perform reference point return on all axes to verify reference position is correctly established. Check POSITION > ABSOLUTE display to confirm coordinates reset to reference position values.

Check DIAGNOSIS > SYSTEM and verify diagnostic number 300 (absolute position status) for each axis. Status showing position not established indicates reference point setup is required.

Mechanically position each axis to the machine reference position (typically using dog switches or mechanical stops). Verify position using dial indicators or mechanical references per machine manufacturer specifications.

Ensure machine is clear of obstructions and coordinate positions with machine tool builder documentation

With axes at reference position, press the soft key or execute the reference position set function to store current position as reference. On most systems this is done via SYSTEM > PMC > KEEP RELAY or dedicated reference set screen.

Set parameter 1815 bit 0 to 0, cycle power, and perform normal reference point return to confirm successful reference establishment.

Check parameter modification history if available (SYSTEM > PARAM > PARAM HISTORY on newer controls) to determine if parameter 1815 was recently changed and by what method.

Review PMC ladder logic (SYSTEM > PMC > LADDER) for any custom programming that writes to parameter 1815 or activates reference position mode based on external conditions or M codes. Search for P1815 references.

If parameter changes were from backup restoration, verify the parameter file source is correct for this machine configuration. Restore from known-good backup or manually set parameter 1815 bit 0 to 0.

Do not restore parameters from different machine models or configurations as this may cause multiple system conflicts