说明：  Modbus 协议是应用于电子控制器上的一种通用语言。通过此协议，控制器相互之间、控制器经由网络（例如以太网）和其它设备之间可以通信。它已经成为一通用工业标准。有了它，不同厂商生产的控制设备可以连成工业网络，进行集中监控。
(Modbus electronic controller is used on a common language. Through this agreement between controller, the controller through the network (such as Ethernet), and other equipment between the communication. It has become a common industry standard. With it, the different manufacturers can even control equipment for industrial network for centralized monitoring.)