The ETS requires the appropriate device certificate for secure commissioning. The device certificate is a string containing the device specific key FDSK (Factory Default Setup Key) and the serial number of a KNX data-secure enabled device. The certificate must be communicated to the ETS.

The FDSK is a factory unique string for each secure device. It is used one time by the ETS to generate additional (digital) keys (tool key/runtime key) for secure communication within the project and saved precisely for this device in the ETS project. If the FDSK is lost, the device cannot be commissioned in secure mode.

When performing a factory reset, the FDSK must be entered in the project again for secure commissioning.

Device certificate




QR code


Factory key

The device certificate is affixed to the side of the device. An extra copy of the device certificate is provided so that it can be removed for secure commissioning with the ETS and then kept in a safe place.

The device certificate is to be removed from the device and stored in a safe place! The FDSK must not fall into the hands of unauthorized parties!