235-0095

Measure total HSCI cable length

Calculate the sum of all HSCI cable segments from the TNC control through all connected devices (encoders, spindle drives, axis drives) back to the control.

Use the cable documentation or physically measure each segment - don't estimate

Check HSCI network topology

Access MOD function and navigate to System Info > Hardware to view the HSCI participant list and verify the network configuration matches the physical installation.

Ensure machine is in a safe state before accessing system diagnostics

Relocate HSCI participants if necessary

If total length exceeds 100m, relocate drives or use HSCI repeaters to segment the network, ensuring each segment remains under the maximum length specification.

Consider using star topology with HSCI hubs to minimize cable lengths

Verify cable specifications

Ensure all HSCI cables meet HEIDENHAIN specifications (impedance, shielding) and replace any non-compliant cables that may cause signal degradation.

Count HSCI participants

Access Setup > General > Machine Parameters and check MP7680 HSCI_PARTICIPANTS to verify the number of connected devices against the 63-device maximum per segment.

Each encoder, drive, and I/O module counts as one participant

Review HSCI network configuration

Navigate to MOD > System Info > HSCI Status to view all active participants and their response times to identify any devices with excessive delays.

Implement network segmentation

If participant count exceeds limits, install HSCI repeaters or hubs to create multiple bus segments, distributing the electrical and timing load.

Power down the system before making HSCI network changes

Update machine parameters

After network changes, update MP7680 and related HSCI parameters to reflect the new network topology and restart the system to reinitialize communications.

Locate HSCI termination points

Identify the physical ends of the HSCI bus network and verify that 120-ohm termination resistors are installed at both ends of each bus segment.

Measure termination resistance

With system powered down, use a multimeter to measure resistance between HSCI+ and HSCI- at each termination point, confirming 120-ohm values.

Ensure system is completely powered down before resistance measurements

Check termination switch settings

Verify that termination switches on HSCI devices are correctly set - only devices at the physical ends of bus segments should have termination enabled.

Replace faulty termination resistors

Replace any termination resistors that don't measure 120 ohms or show signs of damage, ensuring proper signal integrity throughout the HSCI network.

Visual inspection of HSCI cables

Inspect all HSCI cables for physical damage, sharp bends, pinch points, or areas where cables may be subjected to mechanical stress or heat.

Pay special attention to cable entry points and areas near moving machine components

Check connector integrity

Verify all HSCI connectors are fully seated and locked, checking for corrosion, bent pins, or loose connections that could cause intermittent communication issues.

Test cable continuity and impedance

Use appropriate test equipment to verify cable continuity and characteristic impedance (should be 120 ohms ±10%) for each HSCI cable segment.

Use only HSCI-compatible test equipment to avoid damaging the network

Assess electromagnetic interference

Check for EMI sources near HSCI cables (VFDs, welders, high-current cables) and reroute or shield HSCI cables as necessary to minimize interference.