Bus coupler 3 insert with external sensor for KNX Features: The bus coupler 3 connects the KNX system to an application module for KNX. The combination of bus coupler 3 and application module represents a functional unit. In the ETS project, this unit is configured in the form of the application program of the application module. In addition, a remote temperature sensor can be connected to the bus coupler 3 with remote sensor. This enables a room temperature controller to record the temperature at an additional measuring point. Notes : The remote sensor functions only in combination with the pushbutton sensor 3 Plus.