The ARJ03P is an RJ45 splitter / junction box which can be used for connecting and splitting any twisted pair based databus which is connected using RJ45 connectors. A typical application example is the expansion of communication and audio transferring busses whereby multiple input and/or output devices are connected to one single peripheral port on a matrix system. Another typical example is the application of an external power supply to a communication bus, for powering the remote in- or output module when the transferred supply voltage has become insufficient due to the long cable lengths. It consists of three RJ45 connectors which are a ‘BUS IN’ and ‘BUS OUT’ connector for making the incoming and outgoing connections while the third connector allows the connection for the remote in- or output module. Two termination jumpers are provided whereby the communication (Pin4 & Pin5) and audio (Pin7 & Pin8) pairs can be terminated at their characteristic impedance (120 Ohm), to ensure a clear communication without reflections. A terminal block connector is provided whereby an external power supply (+24 V DC) can be connected to the bus. The +24 V DC is available on RJ45 Pin3 (+) and Pin6 (GND). The unbreakable plastic housing allows easy mounting on Mini DIN rails.