The Universal Interface has 2 channels that can be parameterized as inputs or outputs, e.g., for connecting conventional pushbuttons, auxiliary contacts, LEDs, and electronic relays. KNX Technical Data: Bus system KNX: Yes; Other bus systems: None; Mounting type: Flush-mounted; With bus coupling: Yes; Number of input channels: 2; Number of inputs: 2; Number of output channels: 2; Protection class (IP): IP20; Sales unit: 1.