KNX bus is widely used for home and building control applications. The KNX interface module is used to connect the Energy Meter to KNX bus. The power supply comes directly from the bus, so that only the bus wiring (a standard twisted pair) must be connected. The interface is provided with an ETS application program, in order to allow for the configuration of the communication. ETS is the standard software for KNX system configuration. All the active and reactive energy, voltage, current, active, reactive, apparent power, power factor, frequency registers available on the measuring instrument can be transmitted over the bus. Transmission modes available are “on request” and “automatic”, based on an adjustable energy account increment (for instance a message every 10 KWh). Status bytes are available as well, containing information about the status of the Energy Meter and the load (type, running tariff, energy import or export and so on).