235-009A

Check HSCI Chain Physical Connections

Inspect all HSCI cable connections between the TNC control and expansion modules. Check MP7440.x entries to identify configured devices.

Power down the system before checking connections to prevent damage to HSCI interfaces.

Verify HSCI Cable Integrity

Test HSCI cables for continuity and proper shielding. Replace any damaged cables with genuine Heidenhain HSCI cables.

HSCI cables are sensitive to EMI - ensure proper routing away from power cables and spindle drives.

Check Device Power Supply

Verify that all HSCI expansion devices have proper 24V DC power supply and status LEDs are indicating normal operation.

Some HSCI devices require separate 24V power even though they communicate via HSCI.

Access HSCI Configuration Parameters

Navigate to MOD function → Machine Parameters → MP7440 (HSCI configuration). Compare configured devices with actual hardware installation.

Use the TNC's diagnostic screen to see the actual HSCI chain detection results.

Verify Device Type and Address Settings

Check that MP7440.x entries match the physical device types and HSCI addresses. Verify device serial numbers match if specified.

Incorrect HSCI addressing can cause communication conflicts with other devices.

Update Configuration Parameters

Modify MP7440.x parameters to match actual hardware configuration. Delete entries for removed devices or add entries for new devices.

Always backup machine parameters before making changes using the TNC's parameter backup function.

Check Device Status Indicators

Examine status LEDs on the suspected HSCI device. Red or flashing LEDs typically indicate hardware faults or communication errors.

Consult the specific device manual for LED status code meanings - each HSCI device type has different indicators.

Perform HSCI Chain Isolation Test

Temporarily disconnect suspected device from HSCI chain and bridge the connection. If alarm clears, the device is faulty.

Ensure proper HSCI chain termination when isolating devices to prevent communication errors.

Replace Faulty HSCI Device

Replace the identified faulty device with a compatible Heidenhain HSCI module. Update MP7440 parameters if device serial number is specified.

Some HSCI devices require firmware updates after replacement - check with Heidenhain service documentation.

Verify HSCI Chain Termination

Check that the last device in the HSCI chain has proper termination resistor installed. Verify no intermediate terminations exist.

Only the last device in an HSCI chain should have termination enabled - check DIP switches or jumper settings.

Check HSCI Chain Topology

Verify HSCI devices are connected in proper daisy-chain configuration without branches or star connections.

HSCI requires strict daisy-chain topology - star or branch connections will cause communication failures.

Test Chain Communication

Use TNC diagnostic functions to test HSCI communication integrity and verify all devices are properly enumerated in sequence.

HSCI device addresses should be sequential starting from address 1 for optimal performance.