231-A940

Check spindle positioning parameters

Navigate to MOD → Machine Parameters → Spindle and verify MP7160 (spindle positioning speed) and MP7161 (spindle positioning tolerance) are correctly set.

Typical positioning speed should be 10-50 RPM for most applications

Verify spindle encoder feedback

Check encoder signals in PLC → Inputs/Outputs → Spindle Encoder. Verify clean quadrature signals and proper index pulse detection.

Ensure spindle is stationary before checking encoder signals

Test manual spindle positioning

Use MDI mode and execute M19 commands to test spindle positioning. Monitor actual vs. commanded position in the position display.

Start with small incremental moves like M19 S0, then M19 S90 to isolate the issue

Check mechanical spindle condition

Inspect spindle for mechanical binding, worn bearings, or excessive friction that could prevent proper positioning.

Perform mechanical inspection only with spindle power OFF and locked out

Verify encoder resolution settings

Check MP7150 (spindle encoder resolution) matches the actual encoder specification. Common values are 1024, 2048, or 5000 pulses per revolution.

Encoder resolution must exactly match the physical encoder specification

Validate encoder scaling factor

Verify MP7151 (spindle encoder scaling factor) is set correctly. For direct-coupled encoders, this should typically be 1.0.

Incorrect scaling will cause position feedback errors and continuous hunting

Check gear ratio compensation

If spindle has gear reduction, verify MP7152 (spindle gear ratio) accounts for mechanical reduction between encoder and spindle.

Calculate gear ratio as encoder revolutions per spindle revolution

Perform encoder calibration

Execute spindle encoder calibration routine through MOD → Calibrate → Spindle Encoder to establish proper reference.

Calibration requires spindle to rotate - ensure work area is clear

Check PLC spindle orientation logic

Review PLC program sections handling M19 spindle orientation. Verify proper interlocks and position control algorithms.

Look for infinite loops or missing position reached confirmations in PLC code

Verify orientation control parameters

Check MP7162 (orientation control gain) and MP7163 (orientation control integration time) for proper tuning values.

Excessive gain can cause oscillation and overshoot

Monitor PLC status during positioning

Use PLC diagnostics to observe spindle orientation status bits and control signals during M19 execution.

Watch for proper sequence: orientation request → positioning active → position reached

Test with different orientation angles

Try various M19 positions (0°, 90°, 180°, 270°) to determine if issue is angle-specific or systematic.

Test only with no workpiece or tooling in spindle

Check drive status and alarms

Monitor spindle drive display for fault codes or status indicators. Check drive parameters for positioning mode configuration.

Most drives have separate parameter sets for speed control vs. position control modes

Verify positioning mode activation

Confirm drive properly switches from speed mode to position mode when M19 is commanded. Check mode selection signals from TNC to drive.

Drive must be in position control mode for spindle orientation to function

Test drive positioning response

Use drive's internal positioning test functions to verify proper servo response without TNC involvement.

This isolates drive issues from TNC control problems

Check power supply and connections

Verify proper DC bus voltage, control signal integrity, and encoder cable connections to the drive.

Check electrical connections only with proper lockout/tagout procedures