开发S7-300/400与第三方软件串口通讯软件！对自行开发上位机工控软件者是非常难得的好资料！网上很难找的！万勿错过！-Development S7-300/400 with third-party software serial communication software! Pairs of self-developed Host Computer Control Software It is very rare good information! Very difficult to fi

vb多线程和西门子PLC通讯程序,用于工业控制系统的监控软件开发.-vb multi-threaded and Siemens PLC communication procedures, control systems for industrial monitoring and control software development.

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!