Abstract: A communication protocol facilitates transmission at maximum rates for various types of cables. The protocol can be used to transmit information between a common control unit and a plurality of spaced apart devices coupled thereto. Alternately, the protocol can be used for transmission of information between devices. One control unit or device transmits clock pulses, while in a low impedance state. The devices respond to the clock pulses and transmit data on the communications link, in a low impedance state, when the source of clock pulses assumes a high impedance state. One or more features of transmitted signals can be used to implement one or more synchronized functions.