According to the present invention, a power source delivers power to a networked device over network cabling (e.g., Ethernet cabling) in one of two modes: a low power mode and a high power mode. The power source begins delivering power at a low power level in the low power mode, and switches to a high...http://www.google.com.hk/patents/US20050044431?utm_source=gb-gplus-share專利 US20050044431 - System and method for operating a sensed power device over data wiring
