The CBD is used to connect the active supply air diffusers ISQ, ISQ-F, and ISQ-V to the combined power supply and communication loop, as well as to connect sensors and other accessories to the diffuser. The box contains a circuit board with detachable screw terminals. Lindinvent's shielded standard cable, with two conductors for power supply (24 VAC) and two twisted pair conductors for communication, is used both for establishing the communication loop and for connecting accessories to the CBD.