摘要本课题的研究对象是PLC，它的实质是一种专用于工业控制的计算机，在现在这个日趋自动化生产的社会发挥着极大的作用。但直接购买的话，PLC的价格比较昂贵，而且买回来的PLC一般至少有八个输入八个输出，而有时需要用到的仅仅是两三个输入输出，这样就造成了资源的浪费，本课题用单片机根据自己的需要来设计PLC，不仅降低了成本，还可以节约资源。

本设计是通过用单片机来代替PLC内部的CPU，也就是把单片机作为PLC的主控元件，根据PLC的接口特性，选择合适的外围器件，和存储器来设计出一种PLC原理样机，然后用单片机的语言来编程实现功能 。75152

PLC被广泛运用于我们的生产生活中，并给我们的生活带来了极大的便利，所以关于PLC的研究是十分有必要的。本设计相较于其他课题并不是很难，实物制作过程中的调试还是会比较麻烦的。

该论文有图33幅，表3个，参考文献20篇。

毕业论文关键词：PLC  单片机 

The Design of Simple PLC based on MCU

Abstract The object of this research is PLC,whose full name is a programmable logic controller, the essence of it is a dedicated industrial control computer,It has played a great role in today's automated production of society increasingly 。However, the price of PLC is too expensive if we buy in stores and it has at least eight input and eight output,however, sometimes we just need two or three input and output, it is a waste of resources, this subject force on designing a simple PLC according to their needs , in this way we can not only reduce costs, but also save resources[1]。

This simple PLC is designed through MCU taking place with the PLC internal CPU, that is,making the MCU as the main element of the PLC, and according to the PLC interface characteristics, selecting the appropriate external components to design a prototype PLC,then we can use the language of microcontroller to write programs and implement some functions[2]。

PLC is widely used in the production of our lives,and has brought great convenience to our lives。 because of this,doing research on PLC is very necessary。 This design is not difficult compared to other subjects, however,the commissioning during physical production may have some trouble。

This paper has 33 figures, 3 tables, 20 references。

Key Words：MCU  PLC 

目  录

摘要Ⅰ

Abstract-Ⅱ

目录Ⅲ

图清单-Ⅳ

表清单-Ⅳ

1 概述-1

1。1课题研究现状- 1

1。2本课题研究目的及意义- 1

1。3本设计的主要工作及结构 2

2 系统硬件设计 4

2。1系统方案确定- 4

2。2系统工作原理10

2。3系统硬件电路14

2。4本章小结20

3 系统软件设计-21

3。1系统软件设计思路21

3。2梯形图-21

3。3编程语言选择22

3。4流程图-23

3。5本章小结25

4 系统软硬件调试26

4。1开发软件介绍26

4。2软件调试过程26

4。3硬件调试过程29

4。4本章小结31

5 总结-32

参考文献33

致谢34

附录35

图清单

图序号 图名称 页码

图2-1 AT89C52管脚图 4

图2-2 TLP521-1光电耦合器 5

图2-3 MAX232引脚 6

图2-4 DB-9和DB-25外形