The weather station detects precipitation events such as rain or snow, wind speed and direction, ambient brightness and dawn/dusk, and receives the radio time telegram. It merely needs to be connected as a network member; the 24 V DC power supply is provided via the four-wire bus line. Radio reception The weather station receives the DCF-77 time telegram, transmitted by radio, with the built-in radio receiver and provides it to the internal real-time clock in the control panel. Light dome for brightness evaluation Four photo sensors arranged at right angles measure the surrounding brightness, whereby sensor 1 also records dawn/dusk values in a second measuring range. Sensor surface to detect precipitation. A switch signal is triggered by the precipitation sensor in the event of precipitation in the form of sprinkle, rain or snow. The sensor surface can be heated. If the outside temperature falls below +15 °C or precipitation is registered, the heater is activated to prevent triggering of a switch signal due to high humidity alone and to avoid ice formation at minus temperatures. After the sensor surface detects precipitation, the heating causes it to dry again quickly. The inclination of the sensor surface creates the angle necessary for water to drain off. Opening for wind measurement Sensors in four openings arranged at right angles measure the wind speed. The direction of the wind is determined by calculating the differences between the sensor values.