23A-0037

Inspect HSCI cable connections

Power down the control and check the HSCI cable at X116 connector on the TNC control and corresponding connector on the inverter module. Ensure locking screws are tight and pins are not bent or corroded.

Disconnect main power and wait 5 minutes for DC bus capacitors to discharge before handling HSCI connections.

Check cable continuity

Using a multimeter, verify continuity on all HSCI cable conductors. The HSCI uses differential signal pairs - check for shorts between signal lines and shield ground.

HSCI cables should not exceed 50 meters total length and must be shielded with 360-degree shield connection at both ends.

Replace HSCI cable if damaged

If cable shows wear, pinching, or continuity faults, replace with genuine Heidenhain HSCI cable (ID: 354770-xx series). After replacement, restart control and verify device appears in MOD > Device Configuration.

Route HSCI cables separately from power cables to avoid electromagnetic interference affecting communication.

Check network termination

Verify terminating resistors are present at both ends of the Profibus (150 ohm active termination) or EtherCAT (100 ohm at last device) network. Check terminator status LEDs if applicable.

On Profibus networks, measure bus resistance between pins 3 and 8 at any node - should read approximately 75 ohms with both terminators active.

Inspect fieldbus cable segments

Examine all cable connections, T-connectors (Profibus), or through-connections (EtherCAT) along the network path. Look for physical damage, loose connectors, or cable strain at connection points.

Do not disconnect EtherCAT cables while control is powered - this will fault the entire network.

Verify device addresses and configuration

Access MOD > Device Configuration > Profibus/EtherCAT Configuration. Check that the device showing error in %2 has correct station address, matches the GSD/ESI file configuration, and shows expected operational state.

Use PLC > Marker Display to monitor Profibus diagnostic markers (system markers 7000-7999 range) to identify specific bus fault conditions.

Test network segment isolation

Temporarily disconnect devices after the failed device to isolate the fault location. If alarm clears, the fault is downstream. Reconnect devices one at a time to identify the failing component or cable segment.

Check device power supply

Verify DC voltage at the device power input terminals. Most Heidenhain peripherals require 24VDC nominal. Check for adequate current capacity from the power supply (check supply loading and voltage under load).

Measure voltage at the device terminals, not just at the power supply output - cable voltage drop can cause brown-out conditions.

Observe device status indicators

Check LED indicators on the peripheral device. Most Heidenhain modules show power (green), communication active (green), and error (red) status. Refer to the specific device manual for LED pattern interpretation.

A rapidly flashing communication LED usually indicates the device is powered but not receiving valid initialization from the master control.

Power cycle the affected device

Remove 24VDC power from the specific device for 10 seconds, then restore power. Monitor the device boot sequence via status LEDs. Access MOD > System Messages to see if the device re-establishes communication automatically.

Some devices require the TNC control to be in a specific operating mode (e.g., not actively machining) to accept re-initialization without a full control restart.