摘  要: 以三种液体混合控制系统为具体设计对象，把三种液体按一定比例混合，在电动机搅拌后要达到要求才能将混合的液体输出容器，并形成循环状态下的一个设计。

该液体混合系统采用基于PLC的控制系统来取代原来由单片机、继电器等构成的控制系统，采用模块化结构，具有良好的可移植性和可维护性。对提高企业生产和管理自动水平有很大的助，同时又提高了生产线的效率、使用寿命和质量，减少了企业产品质量的波动，因此具有广阔的市场前景。液体混合自动配料系统就此应运社会工业生产的需要而诞生了。

液体混合系统的控制设计能够实现安全、高效的运行。同时考虑到其动作的连续性个，对于不同的工作状态，进行相应的动作控制输出，从而实现液体混合系统从第一种液体加入到混合完成输出的这样一个周期控制工作的程序实现。设计以液体混合控制系统为中心，从控制系统的硬件系统组成、软件选用到系统的设计过程（具体内容包括混合搅拌控制方案的设计、软硬件电路的设计、常见故障），旨在对其中的设计及制作过程做简单的介绍和说明。设计采用西门子公司的S7-200系列去实现设计要求。74003

毕业论文关键词：多种液体，西门子S7-200系列机型，自动控制

Abstract：The three kinds of liquid mixing control system for the design of the object, the three liquids are mixed according to a certain proportion, stirring after the motor to reach the control requirements can be mixed liquid output containers, and formed a design cycle condition。

The liquid mixing system using PLC based control system to replace the original control system composed of single-chip computer, the relay and so on, uses the modular structure, it has good portability and maintainability。 There are a lot of help to improve the automatic level of enterprise production and management, and improve the efficiency, the production line and quality of life, reduce the enterprise product quality fluctuation, it has broad market prospects。 Liquid mixing automatic batching system to need to be social and industrial production was born。

Liquid hybrid systems control design to achieve security, efficient operation。 taking into account the continuity of its action, for different working conditions, carries on the corresponding action control output, so as to realize the liquid mixing system realized a cycle control of the program from the first liquid added to the mixture to complete the output。 Design with liquid mixing control system as the center, composition, control system from the hardware software system to choose the design process (specific content includes mixing control scheme design, hardware circuit design, fault), aims to design and manufacturing process which made the simple introduction and notes。 The design is adopted to achieve the design requirement Siemens Company S7-200 series。

KEY WORDS: A variety of liquid, Siemens S7-200 series machines, automatic control

目 录

1 绪论 3

1。1 本课题的目的和意义 3

1。2 本课题现有技术情况 4

1。3 本课题应解决的主要问题及技术要求 5

2 系统设计和常见故障分析维护 6

2。1 总体结构 6

2。2 控制系统设计过程及控制要求 6

2。3 系统故障分析及处理 7

2。3。1 PLC主机系统故障分析及处理 7