modbus串口通信，利用vc6.0控件自己的项目中用到的代码，很好用。里面有两个程序，一个上位机，一个模仿下位的极的程序，可以互相通信。-modbus serial communication, the use the code the vc6.0 controls used in the project, to very good use. There are two programs, a host computer, an imitation of a bit extreme progr