A Power Over Ethernet, PoE, system, the PoE system including Power Sourcing Equipment, PSE, (40, 112) configured to provide data and voltage over Ethernet wires, the PSE having a voltage source configured to generate a PoE voltage for transmission on the Ethernet wires, the PoE system comprising: a Powered Device, PD, (42, 108) connected to the PSE by at least the Ethernet wires (18, 20) to receive the data and voltage, the PD comprising a first circuit (44, 106) electrically coupled to input terminals of the PD, wherein the first circuit is configured to respond to a first signal generated by the PSE to create a second signal, and wherein the first circuit is configured to cause the second signal to convey particular PoE requirements of the PD, the particular PoE requirements comprising a power level required by the PD; the PSE (40, 112) further comprising: a first signal generator (60, 120) configured to provide the first signal on the Ethernet wires to the input terminals of the PD at a particular time, wherein the PD is configured so that the first signal is applied to the first circuit in the PD; a first detector (122, 124) configured to detect the second signal, generated by the first circuit in the PD, in response to the first signal and during application of the first signal to the first circuit in the PD, the second signal having a ramping magnitude; and a processing circuit (62, 58, 68, 126, 118, 130) configured for detecting a time elapsed between a detection that the magnitude of the ramping second signal crosses a reference value and the starting of the providing of the first signal on the Ethernet wires and, in response to detecting the time elapsed, determining as a function of the time elapsed the conveyed particular PoE requirements of the PD, and controlling the PSE to supply power to the PD via the Ethernet wires consistent with the PoE requirements of the PD conveyed by the second signal. a Powered Device, PD, (42, 108) connected to the PSE by at least the Ethernet wires (18, 20) to receive the data and voltage, the PD comprising a first circuit (44, 106) electrically coupled to input terminals of the PD, wherein the first circuit is configured to respond to a first signal generated by the PSE to create a second signal, and wherein the first circuit is configured to cause the second signal to convey particular PoE requirements of the PD, the particular PoE requirements comprising a power level required by the PD; the PSE (40, 112) further comprising: a first signal generator (60, 120) configured to provide the first signal on the Ethernet wires to the input terminals of the PD at a particular time, wherein the PD is configured so that the first signal is applied to the first circuit in the PD; a first detector (122, 124) configured to detect the second signal, generated by the first circuit in the PD, in response to the first signal and during application of the first signal to the first circuit in the PD, the second signal having a ramping magnitude; and a processing circuit (62, 58, 68, 126, 118, 130) configured for detecting a time elapsed between a detection that the magnitude of the ramping second signal crosses a reference value and the starting of the providing of the first signal on the Ethernet wires and, in response to detecting the time elapsed, determining as a function of the time elapsed the conveyed particular PoE requirements of the PD, and controlling the PSE to supply power to the PD via the Ethernet wires consistent with the PoE requirements of the PD conveyed by the second signal. a first signal generator (60, 120) configured to provide the first signal on the Ethernet wires to the input terminals of the PD at a particular time, wherein the PD is configured so that the first signal is applied to the first circuit in the PD; a first detector (122, 124) configured to detect the second signal, generated by the first circuit in the PD, in response to the first signal and during application of the first signal to the first circuit in the PD, the second signal having a ramping magnitude; and a processing circuit (62, 58, 68, 126, 118, 130) configured for detecting a time elapsed between a detection that the magnitude of the ramping second signal crosses a reference value and the starting of the providing of the first signal on the Ethernet wires and, in response to detecting the time elapsed, determining as a function of the time elapsed the conveyed particular PoE requirements of the PD, and controlling the PSE to supply power to the PD via the Ethernet wires consistent with the PoE requirements of the PD conveyed by the second signal.