230-044B

Access handwheel configuration

Press MOD key, navigate to System → CfgHandwheel → type parameter to check current handwheel type setting.

Document the current setting before making changes for rollback purposes.

Verify physical handwheel model

Check the handwheel label for exact model number (HR410, HR420, HR550, etc.) and compare with the configured type parameter.

Ensure machine is in safe state before accessing handwheel connections.

Correct configuration mismatch

Set System/CfgHandwheel/type to match the physical handwheel model, save parameters, and cycle power to TNC control.

Use machine manufacturer documentation to verify supported handwheel types for your specific TNC version.

Inspect handwheel cable connections

Check both ends of handwheel cable for loose connections, corrosion, or physical damage at the handwheel unit and TNC control cabinet.

Power down the TNC control before disconnecting any handwheel cables.

Clean and reseat connections

Clean connector contacts with appropriate contact cleaner and firmly reseat all handwheel cable connections.

Apply dielectric grease to outdoor or high-humidity installations to prevent future corrosion.

Test cable continuity

Use multimeter to verify continuity on all handwheel cable conductors, particularly the data transmission lines.

Handwheel cables typically use shielded twisted pair for data lines - check shield continuity as well.

Replace cable if defective

Install new handwheel cable if continuity test fails, ensuring proper routing away from high-voltage motor cables.

Use only Heidenhain-approved handwheel cables to maintain proper impedance and shielding.

Verify handwheel power supply

Check voltage at handwheel connector using multimeter - should be 5VDC ±5% on appropriate pins per Heidenhain wiring diagram.

Measure voltage with handwheel connected to verify proper loading conditions.

Test with known good handwheel

Temporarily substitute a verified working handwheel of the same type to isolate whether the issue is with the handwheel unit itself.

Ensure replacement handwheel is exactly the same model to avoid configuration conflicts.

Check handwheel LED indicators

Observe handwheel status LEDs during operation - abnormal blinking patterns indicate internal encoder faults.

Refer to handwheel manual for specific LED diagnostic codes for your handwheel model.

Replace defective handwheel

Install new handwheel encoder unit if internal failure is confirmed, ensuring proper configuration in System/CfgHandwheel parameters.

Consider upgrading to newer handwheel model if current unit is obsolete.

Check TNC handwheel interface signals

Use oscilloscope to verify proper data signal levels at TNC handwheel input connector during handwheel operation.

Look for clean square wave signals at appropriate voltage levels per TNC interface specifications.

Verify TNC power supply voltages

Measure all TNC internal power supply voltages, particularly the 5VDC rail used for handwheel interface circuitry.

Only qualified technicians should access TNC internal power supplies due to high voltage hazards.

Test with minimal configuration

Disconnect all other peripherals and test with only one handwheel to isolate TNC interface problems from system loading issues.

This helps determine if the issue is interface capacity or hardware failure.

Contact Heidenhain service

If TNC interface hardware failure is confirmed, contact Heidenhain service for repair or replacement options.

Attempting TNC internal repairs will void warranty and may cause additional damage.