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Manually jog the affected axis in both directions with handwheel or incremental jog to check for binding, unusual resistance, or mechanical obstructions. Listen for abnormal sounds from ballscrew, bearings, or coupling.

Check parameter 1826 (torque control position error limit) for the alarmed axis. Typical value is 500-2000 (increments). Navigate to SYSTEM > PARAM and search for parameter 1826. Verify value is appropriate for your application - too small a value causes nuisance alarms.

Review parameter 2820 (torque limit in torque control mode) - typically 0-1000 representing 0-100% of rated torque. If set too high, excessive force may cause binding. If too low, axis cannot overcome normal resistance and position error accumulates.

Check DIAGNOSIS screen 300 (position deviation) while manually moving axis. Navigate to SYSTEM > DIAGNOSIS > 300. Monitor real-time position error - values consistently above 50% of parameter 1826 indicate mechanical issues or servo tuning problems.

Do not operate in torque control mode with known mechanical binding - risk of machine damage or collision

Check parameter 1825 (position loop gain) for the alarmed axis. Navigate to SYSTEM > PARAM, search 1825. Typical range 20-60 (0.01 rad/s units). For torque control applications, start with lower values (20-30) to reduce position stiffness and prevent hunting.

Verify parameter 1622 (velocity loop gain) and 1624 (velocity loop integration time constant). Navigate to SYSTEM > PARAM. Standard values: 1622=30-50, 1624=16-64ms. Improperly tuned velocity loop causes poor torque response and position instability.

Check servo amplifier LED status during alarm. Red LED solid indicates alarm state. After clearing alarm, observe during test - flashing patterns indicate specific amplifier faults. Refer to amplifier label for LED code meanings (αi series: 1-flash=overcurrent, 2-flash=overvoltage, etc.).

Review parameters 1560-1563 (rapid traverse rate) and 1420-1423 (maximum cutting feedrate) to ensure commanded speeds during torque control are within mechanical capability. Excessive speed commands exacerbate position error accumulation in torque mode.

Check DIAGNOSIS screen 200-207 (encoder feedback) for the alarmed axis. Navigate to SYSTEM > DIAGNOSIS > 200-207. Look for A/B phase pulse counts - values should increment smoothly during motion. Erratic jumps or frozen counts indicate encoder or cable issues.

Inspect encoder cable routing for damage, sharp bends (minimum 10x cable diameter radius), proximity to power cables, or loose connections at motor and amplifier. Check encoder connector pins for bent pins, contamination, or corrosion. Re-seat connections firmly.

Power off CNC and servo amplifiers before disconnecting encoder cables to prevent damage

Check DIAGNOSIS screen 220 (serial encoder communication status) if using serial encoder (αi series). Values should show 0 (normal). Non-zero values indicate communication errors. Also check parameter 2000 (encoder type setting) matches installed encoder.