结合西门子S7-200系列PLC的特点,介绍了由PLC和计算机构成的分布式监控系统,分析了RS232和RS485的通信方式及通信原理,着重阐述了系统的硬件连接、通信协议和利用VB实现计算机与PLC的通信方法,并给出了详细的程序设计过程。该系统对于用计算机对PLC实现数据集中采集、监控提供了可靠的手段。
Combination of Siemens S7-200 series of PLC characteristics,Introduced by PLC and a computer distributed control system,Analysis of RS232 and RS485 communication method and communication theory,focuses on the system hardware connection,communication protocols and realization by VB computer and PLC communication method,and gives a detailed program design process.The system for the computer to PLC implementation of centralized data acquisition,monitoring provides a reliable means of.