图7-4 设备属性设置
图7-5 编写脚本程序
丁家根：基于PLC水厂滤池自动控制系统的设计
结论与展望
本论文设计的是水厂过程自动控制系统中的滤池过滤控制环节，系统的设计主要是针对滤池恒水位过滤和自动反冲洗环节的控制方案的解决。当滤池没有接收到强制反冲洗信号、长时间过滤导致的水头压力损失信号以及滤池的反冲洗周期信号时，滤池工作在恒水位的过滤阶段，从而保证水厂出水的品质。本系统要求滤池水位保持在0.5-2.5m高度范围以内进行正常的过滤，为了达到系统的要求，本控制系统采用的是一般的控制系统。
毕业设计作为本科阶段的一个最重要的理论和实际相结合的学习过程，同时也是为即将步入社会的我检验自己所学专业领域基础知识掌握程以及不足提供了一个平台。我目前已在实习，而且将来的工作大多是关于PLC方面的知识。通过这次毕业设计，从加深对本专业领域基本知识和技能的角度来讲，我得到了不少的提高，增长了不少的见识和兴趣;但是从自己对本专业知识和技能的理解与掌握的欠缺程度来衡量的话，理解的深度函待加强，实际的应用能力有待提高，知识面涉猎的广度更待进一步的拓宽。实际应用知识也很欠缺，为此，已经走向工作岗位的我，还要认真学习这方面的知识，尤其是PLC、变频器、DCS等专业知识。
本次设计综合了较多的专业课知识，比如，PLC、计算机控制技术、计算机语言、自动控制原理、传感器等等。
通过本次设计，使专业课方面知识有了进一步地学习尤其是PLC方面知识，还要学习其他型号PLC，比如Siemens-s7系列、欧姆龙CQM系列，为将来学习、工作做了良好铺垫。
XXII
致 谢
在论文完成之际，回顾整个设计过程，首先我要特别感谢陈其工老师的研究生许培学长。我本人四月份开始在公司实习，毕业设计方面没有花太多时间，尤其是学期后期公司方面比较忙，感谢他对我的体谅与理解，并且多次关心论文的进度情况，尤其是要交初稿时，虽然我不在学校，给交流带来了一定的困难，但他对我认真指导，指出我的论文存在诸多的不足与毛病，在他的耐心指导下，完成了本次毕业设计。
毕业设计作为本科阶段的最后一个环节，把我们整个大学期间专业领域知识量的积累提升到质的飞跃。在设计过程中，培养了我发现问题，分析问题和解决问题的能力，也使我学到了很多课本无法涉及到的知识体会到了工程设计的复杂与艰辛，也初次尝试到拥有属于自己的一点小小成功的那份喜悦。此次毕业设计能完美的结束，是我个人的努力，更是同学和学长的支持与帮助的结果。在此感谢同组的同学对我的帮助，感谢他们仔细的为我寻找设计中的缺陷，感谢他们耐心的为我解答难题。
总之，毕业设计带给我的远远不是这儿句话可以表达的。劳动是艰辛的，合作是快乐的，收获是甜美的。即将迈进社会，但这并不意味着我们和学习分手。事实上我们已经站在了一个新的起跑线上。此时的我们应该更加沉稳和自信，已经迈出校门的我，会更加努力学习，继续饯行学校“三做”育人理念，不断提升自己综合素质。
前途一片光明，生活充满希望，道路漫长崎岖，过程充满艰辛，希望即将步入社会熔炉的我们都能够百炼成钢!
最后，向自动化答辩委员会致以崇高的敬意!向担任本次自动化专业毕业设计评答辩的所有老师们表示我最衷心的感谢和美好的祝福!
作者：
2012年6月13日
丁家根：基于PLC水厂滤池自动控制系统的设计
参考文献
[1] 李展峰，邹振裕. 水厂滤池自动反冲洗控制[J]. 电气应用, 2008,(08) . [2] 陈晓. PLC在水厂自动控制系统中的应用[J]. 电工技术, 2009,(06) .
[3] 束庆和. PLC控制技术在污水处理系统中的应用[J]. 科技资讯, 2009,(04) . [4] 王会敏,韦文广.基于plc的水厂滤池控制[J]. 自动化技术与应用, 2009,(05) [5] 韩庆瑶,王建英,袁兴华.plc在水处理控制系统中的应用 [J]. 机械设计与制造,2007,(09)
[6] 邹振裕, 罗永恒, 李展峰.水厂滤池自动反冲洗控制的优化研究[J].工业水处理, 2011,(01)
[7] 张伟, 马龙华, 钱积新. PLC在自来水厂滤池控制中的应用[J].化工自动化及仪表, 2002,(01)
[8] 杜慧琳. 浅谈基于plc的水厂控制[J]. 科技风, 2009,(05) . [9] 李辉. 浅谈plc在水厂中的应用[J]. 科技创新导报, 2009,(16) .
[10] 张建煜, 吴文红. 水厂滤池自动化系统的方案设计[J]. 电工技术, 2006,(04). [11] 高钦和. 可编程控制器应用技术与设计实例[M].北京:人民邮电出版社,2004,07. [12] 汪晓平. PLC可编程控制器系统开发实例导航[M].北京:人民邮电出版社,2004,07. [13] Mihaela Frigura、Flaviu Mihai Frigura.Technical solutions concerning the updating of Resita’s waste water plant .ANUL XII, NR.1, 2005, ISSN 1453-7394.
[14] Rob Mackenzie, MSAIEE, Phoenix Contact. The future of automation –profinet. February 2006.
[15] Chris du Toit, WSP Consulting Engineers .The design, documentation and maintenance of PLC software May 2006.
XXIV
附 录A
参考外文文献原文
The design, documentation and maintenance of PLC software
By ChrisduToit, WSP Consulting Engineers
There are a little of books, courses or training manuals on the design, documentation and maintenance of programmable logic control (PLC) software. Many people are also keep the opinion that if PLC software works (i.e. it performs its intended function), it is good software and if it does not work, it is bad software. If software is written for an application where it will be commissioned and never touched again (neither for alterations nor for fault-finding), the effectiveness thereof can essentially be measured by how good the control is. Such applications however are few and far between, and do not warrants further discussion. By far the vast majority of software applications are used where someone (usually not the designer) will access it for fault-finding and/or alterations. There are applications where modifications must be made to an existing PLC (which might be relatively full in terms of memory capacity) or there might be an application in a new PLC where memory capacity is limited. In such cases the effectiveness of the software is measured by its effective use of available memory. Other good software principles might therefore have to be scarified cud in order to provide software for minimum memory consumption.
In most Cases however, memory is relatively cheap and therefore not a huge problem. We can thus concentrate on the issues related to the majority of PLC applications.
Many other areas can still be defined if required. The principle however, shows that specific data areas are reserved for specific functions. The advantage is that if one has to add to the software, one knows in which areas of the database to look for spare words, registers, if les or coils, rather than searching through an entire database consisting of very haphazard allocations. In some PLCs these data areas can even be made “local” to a specific section of software code. This will ensure that data from one area cannot accidentally be used in the wrong area. Similarly, by merely looking at an address, one can tell whether the data comes from a radio telemetry system, another PLC, a SCADA system or whether it was generated within the software code. External devices such as SCADA systems, radio telemetry systems and other PLCs on a network can then also be configured in a standard way for data exchange. All these factors contribute to quality control as well as the ease and speed with which software can be evaluated and/or modified.
Flags, outputs or coils generated internally should be annotated to describe the function it actually performs, and not the function it will eventually perform. For example, if a bit has to be set when several interlocks are healthy, and this bit is then later used to start a pump, the bit should be annotated as “All Interlocks Healthy”, rather than “Start Pump”. This will
ensure that when someone else evaluates the software, he can see what causes that particular bit to be on or off, rather than having to search for the code which controls it, to establish how it functions.
基于plc的水厂滤池自动控制系统设计本科毕业论文
