本源代码演示了通过串口利用MPI协议与西门子PLC S7-300系统通讯的实现方式。,Demo source code through the serial port using MPI agreement with Siemens PLC S7-300 system, ways of communication.

利用第三方软件（如VB）开发S7-300PLC与上位机进行MPI通讯的源码实例！非常珍贵！-The use of third-party software (such as VB) development of S7-300PLC to MPI communication with the host computer source code examples! Very precious!