A cable with circuitry that enables the cable to communicate data in one of at least two different signal modes of operation is presented. In a first signal mode, the cable enables data communication between the circuitry and either a source device or a sink device. The first signal mode can be used either to communicate properties of the cable itself or of a signal passing through the cable to either the source device or the sink device. In a second signal mode, the cable enables data communication between the source device and the sink device. The second signal mode can be used to communicate data in accordance with a predetermined protocol.