Power over Ethernet (PoE) communication systems provide power and data communications over the same communications link, where a power source device (PSE) provides DC power (for example, 48 volts DC) to a powered device (PD). The DC power is transmitted simultaneously over the same communications medium...http://www.google.com/patents/US20070206774?utm_source=gb-gplus-sharePatent US20070206774 - Apparatus and method for classifying a powered device (PD) in a power source equipment (PSE) controller
