EtherCAT对PHY有要求？

/**********************************************************************
 *                     EtherCAT对PHY有要求？
 * 说明：
 *     之前常听说EtherCAT对PHY有特殊的要求，于是找点资料确认一下，结论
 * 是没有什么特殊的要求，另外就是EtherCAT和CANOpen类似通过配置文件进行
 * 功能配置。
 *
 *                                2018-11-30 深圳 宝安西乡 曾剑锋
 *********************************************************************/

一、参考文档：
    1. EtherCAT
        https://en.wikipedia.org/wiki/EtherCAT
    2. EtherCAT主站开发经验——基于X86或ARM
        https://jingyan.baidu.com/article/6181c3e0844e7d152ef15332.html

二、Ethernet和EtherCAT在7层网络（ISO/OSI Reference Model）架构上的区别：
    1. The TCP/IP Stack shown is not needed for typical fieldbus devices.
    2. EtherCAT master can access all data including name and data types of an EtherCAT slave without complex tools.
    3. EtherCAT uses Standard Ethernet (IEEE 802.3 - Ethernet MAC and PHY) without modifications.

三、 Device Profiles：
    The device profiles describe the application parameters and functional behavior of the devices, including device-specific state machines. The following software interfaces are provided for existing device profiles. Thus, the migration to EtherCAT by adjusting the firmware and the hardware is simplified significantly.