现代工业应用中，串行通信是一种使用相当广泛的通信方式，其配线数少，容易实现，长久以来一直被广泛采用。而Visual Basic 在开发可视化环境下的监控系统时具有其独特的优势，倍受青睐。本文以VB 在西门子PLCS7-300 与上位机通信中的应用为例，提出了VB在串行通信中一种新的应用方法。关键词：Visual Basic；可编程控制器；串行通信；上位机Abstract: Serial communication is a widely used communication method in the applications ofmodern industry. It has little wiring and is easy to realize. So it has been used for a long time.Moreover, Visual Basic has its special advantage in development of inspection system in viewable environment. This paper takes the communication between SIMATIC S7-300 and the computer as an example, puts forward the new idea of the usage of Visual Basic in serial communication.Keywords: Visual Basic; PLC; serial communication; host computer