For safe commissioning, the ETS requires a suitable device certificate. The device certificate is a string containing the device-specific FDSK (Factory Default Setup Key) and the serial number of a KNX Data Secure-enabled device. The certificate has to be communicated to the ETS.

The FDSK is a factory unique string for each Secure device. The ETS uses it once to create further (digital) keys (tool key/runtime key) for secure communication within the project. The FDSK is stored in the ETS project for this specific device. If the FDSK is lost, the device cannot be started in secure mode.

In case of a reset to factory settings, the FDSK must be entered again for secure start-up within the project.

Device certificate




QR code


Factory key

The device certificate is affixed to the side of the device as a sticker. There is a duplicate device certificate, which can be removed for easy commissioning with the ETS and stored in a safe place.

The device certificate must be removed from the device and stored securely. The FDSK must not fall into the hands of unauthorised persons.