毕业设计 PC与PLC的通信系统（下位机）设计.docVIP

毕业设计（论文） 中文题目 PC与PLC的通信系统（下位机） 英文题目 PC and PLC communications system (lower position machine) PC与PLC的通信系统（下位机） 摘 要 计算机技术在其发展过程中形成两个重要分支：通用计算机领域，现在以PC机为代表，着重发展海量高速数值运算技术，而其控制能力是有限的；嵌入式计算机领域，现在以PLC为代表，着重发展计算机的控制技术，而其计算机速度是有限的。在目前的许多实时工业控制和数据采集系统中，常常采用PC机做上位机和多个PLC做下位机的主从式系统。在主从分布式控制系统中，PLC主要完成实时数据采集，被采集数据经初步处理后通过串口传送给主机。主机将从机发送来的数据进行处理后随时向用户提供各种统计报表和整个控制过程的具体数据。主机同时根据从从机接收的过程参数进行判断处理并给从机(PLC)发送各种控制命令。它既利用了PLC的价格低、功能强、抗干扰能力强、温限宽和面向控制等优点，又利用PC机操作系统的高级用户界面、多任务、自动内存管理等特点。PLC与微机的串行通信可以弥补PLC在数据处理方面的不足和PC机在控制方面的欠缺。本文论述了其中一个分支:嵌入式计算机即PLC,分析PLC通信方式,对PLC通信系统进行设计开发，且详细介绍了PLC的结构特点、通信接口的功能,PLC自由口通信的原理及过程。 关键词 自由口通信； PC； PLC ABSTRACT The abstract computer technology forms two important branches in its developing process: The general-purpose calculator domain, now take PC machine as representative, develops the magnanimous high speed value operation technology emphatically, but its control is limited; The embedded computer domain, now take PLC as representative, develops the computer control technology emphatically, but its computer speed is limited.In the present many real-time industry control and in the data acquisition system, uses PC machine to make the position machine frequently and many PLC is the lower position machine host from the type system.In the host from the distributional control system, the monolithic integrated circuit mainly completes real-time data gathering, is gathered the data to transmit after preliminary processing through the serial port for the main engine.The main engine will carry on processing after machine the transmission data as necessary to provide each kind of statistical report form and the entire controlled process concrete data to the user.At the same time the main engine acts according to the high machine receive the process parameter to carry on judgment processing and for transmits each kind of control command from machine (PLC).It both used the PLC price lowly, the function strong, antij