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Check standstill monitoring parameters

Access MOD function → Machine Parameters → Axis-specific parameters and verify MP1715 STANDSTILL_WINDOW and MP1716 STANDSTILL_TIME settings are appropriate for axis condition.

Typical standstill window values range from 0.001-0.005mm depending on axis precision requirements

Perform mechanical inspection

Manually move axis and check for excessive backlash in ball screw, coupling, and bearing assemblies. Measure backlash with dial indicator.

Ensure machine is in emergency stop before manual inspection

Monitor position feedback

Use TNC diagnostic screen (MOD → Diagnosis → Servo) to observe actual position values during standstill periods for micro-movements exceeding standstill window.

Look for position drift patterns that indicate specific mechanical wear locations

Check encoder cable connections

Inspect encoder cable connections at motor, junction boxes, and TNC control for loose, corroded, or damaged pins. Verify proper shielding continuity.

Power down system before disconnecting encoder cables to prevent damage

Monitor encoder signal quality

Access MOD → Diagnosis → Encoder signals and check for signal amplitude, offset errors, and interpolation error values. Verify signals are within specification ranges.

Encoder interpolation errors should typically be less than ±80 counts for proper operation

Test with encoder cable isolation

Temporarily reroute encoder cables away from power cables and VFDs to eliminate EMI sources, then test standstill recognition functionality.

Use oscilloscope to check for high-frequency noise on encoder differential signals if available

Verify servo drive parameters

Check servo drive configuration matches TNC machine parameters, particularly MP1020 MOTOR_RATED_CURRENT and MP1025 MOTOR_STANDSTILL_CURRENT settings.

Standstill current should typically be 50-70% of rated motor current for optimal holding without overheating

Review current loop tuning

Access servo drive parameters and verify current loop proportional and integral gains are properly tuned for the motor/load combination.

Improper current loop tuning can cause motor instability and potential damage

Perform servo optimization

Use TNC automatic servo optimization function (MOD → Machine → Servo optimization) to retune position and velocity loops for current mechanical conditions.

Run optimization with typical load conditions for best real-world performance

Identify vibration sources

Check for external vibration sources such as nearby machinery, HVAC systems, or building vibrations affecting machine foundation stability.

Use smartphone vibration apps or accelerometers to quantify vibration levels during standstill periods

Adjust standstill parameters

Temporarily increase MP1715 STANDSTILL_WINDOW value to accommodate environmental vibrations while maintaining acceptable positioning accuracy.

Increasing standstill window may affect machining precision - use minimum value that eliminates false alarms

Implement vibration isolation

Install vibration dampening pads under machine or isolate specific axis components if structural modifications are feasible.

Focus isolation efforts on the specific axis experiencing standstill issues rather than entire machine