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Review the NC program at the point of alarm occurrence. Check for G150, G151, or other composite control activation/deactivation codes and verify that G04 dwell or M00/M01 stop commands precede the composite control command to ensure axis settling.

Navigate to SYSTEM > DIAGNOSIS screen and check diagnosis numbers 300-303 (axis load meter) and 400-403 (servo position deviation) for the composite axes to confirm motion has stopped and in-position status is achieved.

Check parameters 1826#0-#7 (in-position check width) and parameter 1827 (in-position check time). If values are too tight, the system may not recognize the axis as stopped. Typical values are 1826=10-50 (0.01mm units) and 1827=100-250ms.

Add a G04 P1000 (1 second dwell) or M00 stop command immediately before the composite control activation/deactivation command in the NC program to ensure complete axis deceleration and in-position confirmation.

Access PMC > PMCDGN screen and monitor G-signals related to composite control (typically G150-G159 range or manufacturer-specific addresses). Capture the signal timing relative to servo ready signals (G027#0-#7 for in-position status per axis).

Review the PMC ladder logic (LADDER > EDIT) for the composite control activation routine. Insert timer functions (TMR instruction) with minimum 500ms delay after detecting in-position signals before activating composite control output to NC.

Verify parameter 1815 (composite control axis specification) correctly identifies the master and slave axis numbers. Incorrect axis assignment may cause the system to monitor wrong axes for motion status.

Check DIAGNOSIS > SERVO screen, diagnosis #400-#407 for position deviation of composite axes. Values above parameter 1826 setting indicate continued motion. Adjust deceleration rates in parameters 1620-1623 (rapid traverse time constants) if necessary.

Modifying acceleration/deceleration parameters affects all machine movements and requires test cuts to verify performance

Navigate to DIAGNOSIS > SERVO screen and monitor diagnosis #300-#303 (servo load) and #200-#207 (position deviation) for the composite control axes during motion stop. Load should drop to near zero (under 5%) and deviation to within parameter 1826 value.

Check servo amplifier LED status codes on the physical drives for the composite axes. Steady green indicates normal, flashing patterns indicate communication or feedback errors. Cross-reference codes with amplifier manual (αi series: A-series, βi series: B-series).

Verify encoder feedback parameters: parameter 1815 (composite axis settings), parameter 1825 (position error detection width), and parameters 1820-1824 (encoder type and resolution). Mismatch between actual encoder and parameter settings prevents accurate in-position detection.

Incorrect encoder parameters can cause servo alarms or runaway. Record original values before changes

Execute servo adjustment procedure from MAINTENANCE > SERVO ADJUST menu. Run auto-tuning for the composite axes to optimize velocity loop gain (parameter 1825) and position gain (parameter 1827) for proper settling characteristics.

Auto-tuning moves axes through full range of motion. Ensure work area is clear and machine in safe state