Patent ID: 8122266
Filing Date: 2012-02-21
Classification: H04L

Abstract:
1. A method of operating a powered communications interface of a power-sourcing equipment, the powered communications interface including coupling circuitry operative to couple data signals between the power-sourcing equipment and conductors of a cable, the method comprising: in a powered operating mode, supplying operating power to a powered device via the coupling circuitry in the form of a relatively high supply voltage across the conductors of the cable and a relatively high supply current through the conductors of the cable; and in a non-powered operating mode, (1) withholding the operating power from the powered device, and (2) applying a sequence of relatively low signaling voltages and relatively low signaling currents to the conductors of the cable via the coupling circuitry, the sequence of relatively low signaling voltages and currents including (a) first signaling voltages and currents of a detection and classification operation by which the presence and power requirements of the powered device are detected, and (b) second signaling voltages and currents of a low-speed communications operation by which the power-sourcing equipment and the powered device exchange operational information outside of the normal powered operation of the powered device, wherein low-speed communications from the power-sourcing equipment to the powered device are conveyed by values and sequencing of the second signaling voltages and wherein low-speed communications from the powered device to the power-sourcing equipment are conveyed by values and sequencing of the second signaling currents which are conducted by the powered device in response to the second signaling voltages from the power-sourcing equipment.