Heidenhain TNC 620 Error Code 305

Heidenhain CNC Major DC Bus

Model: TNC 620 | Code: 305

Applicable Systems
TNC 620

Symptoms

Drive voltage fault. The servo drive DC bus voltage is outside the allowed range.

Possible Causes

  • DC bus overvoltage from regenerative energy
  • DC bus undervoltage from line voltage drop
  • Brake chopper resistor fault
  • DC bus voltage measurement circuit fault

Troubleshooting Steps

  1. Step 1: Check the equipment status and fault indicators to confirm the active fault code
    Fault indicator or HMI displays code 305 as active
  2. Step 2: Verify all electrical connections, wiring harnesses, and connector seating
    All connections secure, no corrosion, loose pins, or damaged wires
  3. Step 3: Check the communication cable continuity and connector seating at both ends
    Cable continuity confirmed, connectors fully seated with locking tabs engaged
  4. Step 4: Verify communication parameters (baud rate, node address, protocol) match network configuration
    All communication parameters match the network setup
  5. Step 5: Inspect cable for EMI interference: check routing away from high-voltage lines and motor cables
    Cable routed away from EMI sources, shielding intact
  6. Step 6: Check terminating resistors at bus endpoints if applicable (e.g., PROFIBUS, CANopen)
    Terminating resistors installed at both bus ends
  7. Step 7: Reset the fault after restoring communication: power-cycle the affected node
    Communication restores and fault clears

How to Reset

To reset: 1) Fix the communication cable or parameter issue. 2) Power-cycle the affected node. 3) Verify communication restores. Caution: Check all nodes on the bus.

Frequently Asked Questions

  • Q: What does fault code 305 mean on the Heidenhain TNC 620?

    Fault 305 indicates a communication fault. The equipment has lost communication with a connected device or network. Check the communication cables, connectors, and network parameters.

  • Q: Can I continue operating the equipment with fault 305 active?

    No. The equipment has detected a fault condition and has taken protective action (typically stopping or derating). Continuing to operate without fixing the root cause may cause further damage. Always investigate and fix the fault before resuming operation.

Related Heidenhain Fault Codes

Source: Heidenhain TNC 620 Operating Manual, Heidenhain Documentation

Category: CNC