西门子ppi与VB的程序，西门子200PLC上位机通信 经典源码-Siemens ppi procedures with VB, Siemens Communications 200PLC classic PC source

本书介绍了基于VB的串口通信的理论知识，并通过大量的例子来详细介绍具体的操作方法和流程，非常经典的一本串口通信方面的书籍。-The book describes the theoretical knowledge based VB serial communication, and by a large number of examples to detail the specific operating methods and processes, a classic serial commu