ALARM 15

Hardware mismatch

Danfoss · VLT HVAC Drive High Power

What does ALARM 15 mean?

A fitted option card is not operational with the current control board hardware or software version. This indicates an incompatibility preventing proper functioning of the option.

Common Causes

  • Option card firmware version is incompatible with the frequency converter's main control board firmware version.
  • Option card hardware revision is not supported by the frequency converter's main control board hardware.
  • Incorrect option card type installed (e.g., I/O card for a fieldbus slot).
  • Option card not properly seated in its slot on the control board.
  • Damaged option card or control board slot preventing correct communication.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the part number and firmware version of the installed option card against the frequency converter's compatibility matrix in the manufacturer's manual.

  2. 2

    Check the frequency converter's control board firmware version (e.g., parameter 15-00 FC Type) and compare it with the option card's requirements.

  3. 3

    Remove the option card and reseat it firmly into its designated slot on the control board, ensuring connectors are fully engaged.

  4. 4

    If available, try installing a known good, compatible option card into the slot to rule out a faulty slot on the main control board.

  5. 5

    Consult the frequency converter manual for specific instructions on option card installation and potential firmware upgrade procedures.

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Verified technical data. Last updated: March 2026

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Source: Danfoss VLT HVAC Drive High Power