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Check the NC program block sequence preceding the coupling command. Verify that an explicit axis stop (e.g., G04 P500 dwell or unconditional stop) is programmed before the CC coupling activation statement.

Ensure the dwell time is sufficient for axis deceleration based on MD32100 (max axis acceleration) and MD36000 (axis load inertia).

Monitor axis velocity in the Diagnostics > Actual Values > Axis menu (NCK menu path: Diag > Axes > [Axis Name] > Act_Vel). Confirm both CC_Master and CC_Slave axes show 0 mm/min or 0 deg/min before re-executing the coupling command.

If using PLC-based coupling logic, check the couple_axis() or CC_MasterSlave FB block. Verify that a motion complete signal (axis.bMoving = FALSE or AXIS_REF.StatusWord bit 0 = 0) is confirmed before the coupling enable input is asserted.

Review MD36050 (Axis standstill time monitoring threshold) to ensure the axis has remained below the standstill velocity threshold (typically 0.1% of max speed) for the required duration before re-triggering coupling.

Verify that a formal program stop (M00 or M01) or axis-specific stop command (STOP) is executed before coupling, not merely a feedrate override reduction. Check the NC program syntax for explicit halt commands before CC_Master/CC_Slave activation.

Measure actual deceleration time by examining trace data: Diag > Kernel > Trace > Configure trace to capture axis velocity of both axes, then trigger coupling and review the time delta between motion stop and coupling command execution.

Deceleration time should equal (max_velocity / MD32110 deceleration value) plus margin.

Check MD32110 (deceleration limit) and MD32105 (jerk limit). If these values are very high, axis standstill detection may be delayed. Temporarily reduce MD36050 standstill velocity threshold in test to confirm if coupling succeeds after a longer settling time.

In the NC program, insert an explicit time delay (G04 P[milliseconds]) calculated as: (axis_max_velocity_mm_min / 60) / (MD32110 deceleration) * 1000 + 200ms buffer, before the coupling activation command.

Inspect the encoder signal quality and wiring for both CC_Master and CC_Slave axes. Use oscilloscope to verify clean encoder signal transitions and proper differential pair termination. Check connector pins at the axis module (typically RESOLVER_1/RESOLVER_2 or ENCODER_A/ENCODER_B).

Loose encoder connectors or damaged cables are common causes of intermittent standstill detection failure.

Verify encoder parameter configuration: Check MD36030 (encoder type), MD36031 (encoder resolution), and MD36032 (encoder direction). Confirm these values match the physical encoder specification and that no encoder faults are logged in Diag > Axis > [Axis] > Errors.