905-2972

Check reference switch status

Navigate to MOD > Machine Parameters > MP7500-7599 (Reference Point) and verify reference switch states in the diagnostic screen.

Use the PLC status display to monitor switch states in real-time during manual movement

Inspect physical switches

Physically examine each axis reference switch for damage, contamination, or mechanical misalignment. Clean switches with appropriate contact cleaner.

Ensure machine power is locked out before accessing limit switches

Verify switch wiring

Check continuity and proper voltage levels at reference switch connections using multimeter. Verify against machine electrical drawings.

Look for intermittent connections by gently flexing cables while monitoring continuity

Test reference point approach

Manually jog axis slowly toward reference switch and observe switch activation point. Adjust MP7500.x (Reference Point Shift) if necessary.

Move axes slowly and be prepared to stop immediately if switch doesn't activate

Check encoder signal quality

Access MOD > Diagnosis > Encoder and examine signal amplitude and quality for all axes. Look for weak or noisy signals in the oscilloscope display.

Encoder signals should show clean square waves with proper amplitude levels

Verify encoder parameters

Check MP4110.x (Encoder Type) and MP4120.x (Lines per Revolution) settings match the installed encoder specifications exactly.

Incorrect encoder parameters can cause permanent position errors

Inspect encoder connections

Examine encoder cable connections at both encoder and drive ends. Check for proper shielding, secure connections, and cable routing away from power cables.

Encoder cables should maintain minimum 6-inch separation from motor power cables

Test reference mark detection

Use the TNC's encoder test function to verify reference mark (index pulse) detection during slow axis movement through the reference position.

Reference mark errors may indicate encoder internal damage requiring replacement

Verify reference point parameters

Check MP7500.x through MP7510.x series parameters for correct reference point direction, speed, and sequence settings for each axis.

Compare current parameters with machine documentation or backup parameter file

Validate axis configuration

Confirm MP1010.x (Axis Designation) and MP1020.x (Axis Enable) parameters match the actual machine configuration and axis count.

Changing axis configuration parameters requires complete system restart

Check homing sequence logic

Review MP7520.x (Reference Point Sequence) to ensure proper homing order, especially for machines with dependent axes or collision risks.

Z-axis should typically reference first to avoid workpiece collisions

Reset and test reference sequence

Clear existing reference status using Manual > Reference Point and execute complete homing sequence while monitoring for proper completion.

Ensure adequate clearance around all axes before initiating automatic reference sequence

Access PLC diagnostics

Navigate to PLC > Diagnosis > Status and examine reference-related markers and timers for proper state transitions during homing attempts.

Look for stuck timers or markers that don't change state during reference sequence

Review PLC reference program

Examine the PLC program sections handling reference point logic, typically in OB1 or dedicated reference function blocks, for logical errors or missing conditions.

Only qualified personnel should modify PLC programs - document all changes

Check safety interlock status

Verify all safety-related inputs and conditions required for reference point operation are satisfied, including door locks, E-stops, and mode selection.

Use PLC force functions carefully to isolate problematic interlock conditions

Test reference enable signals

Monitor PLC outputs that enable reference point operation and verify they activate properly when reference sequence is initiated from the TNC.

Forcing reference enable signals bypasses safety systems - use extreme caution