Abstract: A coupler assembly for noninvasive coupling to conductor wires of a twisted pair cable of a data bus uses mating pairs of E-shaped electromagnets defining a pair of electromagnet cores having windings about central legs thereof electrically connected to a control unit for sensing and transmitting signals along the data bus. A lower member with lower electromagnets is mounted to a panel, while an upper member with upper electromagnets includes a circuit substrate having trace windings about substrate apertures receiving the central legs of the upper electromagnets, an electronic subassembly to which the windings are electrically connected to amplify signals received and signals to be sent, and a shielded electrical connector secured at a connector end connected to circuits of the electronic subassembly and matable with a connector of a cable extending to the control unit.