模拟传输与数字传输、通信的几个基本概念、传输线、现场总线（含工业以太网）概述、现场总线协议、各种现场总线。 -Analog transmission and digital transmission, a few basic concepts of communication, transmission lines, fieldbus (including Industrial Ethernet) overview Fieldbus protocol, a variety of field

Ethernet protocol and basic comunication

Ethernet communication protocol