FX3U 串口通讯程序实例。该类通讯组件适用于基于PC高级语言的工业自动化控制系统，用于PC与可编程控制器(PLC)、智能仪表等进行数据通讯。组件采用动态链接库文件(*.DLL)的形式，在PC系统的项目工程里引用该组件，调用相应的属性与方法函数，即可快速实现PC与PLC的数据高效交换。(FX3U serial communication program examples. This kind of communication component is suitable for industrial automation control system based on PC high-level language, which is used for data communication between PC and programmable logic controller (PLC), smart meter and so on. The component uses the dynamic link library file (* .DLL) to refer to the component in the project of the PC system and call the corresponding properties and method functions to realize the efficient exchange of data between the PC and the PLC.)