38.0

Internal Fault: Serial port initialization error

Danfoss · VLT HVAC Drive FC 102

What does 38.0 mean?

The internal serial communication port failed to initialize upon power-up or during operation. This can prevent communication with the LCP or external serial devices, indicating a possible internal hardware or firmware issue with the control board.

Common Causes

  • Local Control Panel (LCP) connection issues; LCP cable is damaged or not fully seated.
  • Faulty LCP module preventing proper communication with the drive's control board.
  • Internal serial communication hardware (UART chip) on the control board has failed.
  • Severe EMI interfering with the internal serial communication lines during initialization.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Power down the drive, then remove and firmly re-seat the LCP on its connector.

  2. 2

    2. Attempt to operate the drive with a different, known-good LCP, if available, to rule out LCP module failure.

  3. 3

    3. Visually inspect the LCP connector on the control board for bent pins or signs of damage.

  4. 4

    4. If the fault persists, replacement of the control board is likely required due to internal serial port hardware failure.

Browse all codes in this manual (75)
Verified technical data. Last updated: March 2026

Related Faults

Source: Danfoss VLT HVAC Drive FC 102