A system for transmitting control systems over twisted pair cabling. The system includes a first microcontroller transmitting a first single ended signal and receiving a second single ended signal. It also includes a first differential transmitter coupled to the first microcontroller for receiving the first single ended signal from the first microcontroller and converting it to a differential signal over a first differential line and a second differential line; and, a first differential receiver coupled to the first microcontroller for receiving a third differential line and a fourth differential line and converting it to a differential receiver signal, the differential receiver signal coupled to the second single ended signal. The system has a first transformer having first, second, third, and fourth center-tapped coils, the first differential line coupled to the center tap of the first coil, the second differential line coupled to the center tap of the fourth coil, the third differential line coupled to the center tap of the second coil, and the fourth differential line coupled to the center tap of the third coil, whereby the common mode of the first transformer is used to transmit a first control signal and to receive control signal responses over the twisted pair at the first processor.