PoE switch work process

POE power switches can be connected with a common computer network card, POE power supply module is adaptive, receiving card device required the requirement of power supply, to supply power to the equipment, if the card device does not require power, POE power supply module is not the transmission current.       POE (Power Over Ethernet)指的是在现有的以太网Cat.5布线基础架构不作任何改动的情况下，在为一些基于IP的终端（如IP电话机、无线局域网接入点AP、网络摄像机等）传输数据信号的同时，还能为此类设备提供直流电的技术.就是支持以太网供电的交换机。    POE (Power Over Ethernet) refers to the existing Cat.5 Ethernet cabling infrastructure does not make any changes in the situation, for some IP based terminal (such as IP telephone, wireless LAN access point AP network camera, etc.) for the transmission of data signals at the same time, can also provide DC technology for this kind of equipment is. Support power over Ethernet switch.       PoE交换机工作过程：    PoE switch work process:       1、检测：poe交换机在端口输出很小的电压,直到其检测到线缆终端的连接为一个支持IEEE802.3af标准的受电端设备。    1, detection: Poe switch in the port output voltage is very small, until it detects the cable terminal connection is a support IEEE802.3af standard receiving end equipment.       2、PD端设备分类：当检测到受电端设备PD之后, poe交换机可能会为PD设备进行分类,并且评估此PD设备所需的功率损耗。    2, PD end device classification: when the detection of the end of the device PD, Poe switches may be classified for PD devices, and to assess the power loss required for this PD device.       3、开始供电：在一个可配置时间(一般小于15μs)的启动期内, poe交换机开始从低电压向PD设备供电,直至提供48V的直流电源。    3, the beginning of power supply: in a configurable time (generally less than 15 s) during the start-up period, Poe switch from low voltage to PD equipment power supply, until the 48V DC power supply.       4、供电：为PD设备提供稳定可靠48V的直流电,满足PD设备不越过15.4W的功率消耗。    4, power supply: PD equipment to provide stable and reliable DC 48V, PD equipment to meet the power consumption does not exceed 15.4W.       5、断电：若PD设备从网络上断开时,   poe交换机就会快速地(一般在300～400ms之内)停止为PD设备供电,并重复检测过程以检测线缆的终端是否连接PD设备。    5, power: if the PD device is disconnected from the network,     Poe switch will quickly (usually 300 ~ 400ms) stops supplying power to the PD device, and repeat detection process to terminal detection cable is connected to the PD device.       一个完整的POE系统包括供电端设备(PSE,Power Sourcing Equipment)和受电端设备(PD, Power    A complete POE system includes a power supply end device (PSE, Power Sourcing Equipment) and a power receiving device (PD, Power)       Device)两部分，poe交换机为PSE设备的一种。PSE设备是为以太网客户端设备供电的设备,同时也是整个POE以太网供电过程的管理者。而PD    Device () the two part, the POE switch is a kind of. The PSE device is a power supply device for an Ethernet client device, and is also the manager of the entire POE Ethernet power supply process. PD       设备是接受供电的PSE负载,即POE系统的客户端。    The device is powered by the PSE load, i.e., the client of the POE system.