外文翻譯--關于plc的控制應用

1、<p>　　PLC Control of the Application</p><p>　　1 Motivation</p><p>　　Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in

2、industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RL

3、L), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days.</p><p>　　Although PC based control has started to come into place,

4、 PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to

5、 a study on the PLC market of Frost and Sullivan[1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices o

6、f c</p><p>　　Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are droppin

7、g continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.</p><p>　　In general, the productivity in generating PLC is far behind compared to o

8、ther domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PL

9、C-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than SO0/a o</p>&l

10、t;p>　　In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigure ability of manufacturing systems. A further problem, impelling the need for

11、a systematic design methodology, is the increasing software complexity in large-scale projects.</p><p>　　1 Objective and Significance of the Thesis</p><p>　　The objective of this thesis is to de

12、velop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discret

13、e event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in

14、managing the control so</p><p>　　A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications

15、 in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system t

16、o be controlled. State machines can be analytically evaluated as to whether or not they meet the desired g</p><p>　　(1) Customer-Driven Manufacturing</p><p>　　In modern manufacturing, systems ar

17、e characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling technologies that can economi

18、cally reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industria

19、l practice.</p><p>　　(2) Higher Degree of Design Automation and Software Quality</p><p>　　Studies have shown that programming methodologies in automation systems have not been able to match rapi

20、d increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a majo

21、r stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60</p><p>　　A systematic approach

22、 will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliabilit

23、y and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.</p><p>　　(3) System Complexity</p>

24、<p>　　The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency

25、. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software

26、 redesign and maintenance-essential in modern automation systems-becomes</p><p>　　(4) Design Theory Development</p><p>　　Today, the primary focus of most design research is based on mechanical o

27、r electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system de

28、sign theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Further</p>&

29、lt;p>　　(5) Application in Logical Hardware Design</p><p>　　From a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely compl

30、ex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single funct

31、ions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is te</p><p>　　關于PLC的控制應用</p><p><b>　　1 前言</b></p

32、><p>　　可編程序的邏輯控制器（PLC），是由Richard E. Morley 于1968年發(fā)明的，如今已經(jīng)被廣泛的應用于生產(chǎn)、運輸、化學等工業(yè)中。當時的PLC以軟式—連線邏輯或所謂的繼電器梯形邏輯（RLL）代替HARDWIRED邏輯，程序的語言看起來像HARDWIRED邏輯，因此構造時間從6個月降到了6天。</p><p>　　雖然現(xiàn)在的PC控制已經(jīng)開始得到應用，但由于PLC的高性能高

33、效率和低價位以及高可靠性，使它仍然廣泛應用于大多數(shù)工業(yè)控制中。而且，根據(jù)在PLC市場或Richard E. Morley的一項研究[1995]，一個每年1500萬件PLC硬件營業(yè)額超過80億美元預言被證實。雖然計算機硬件的價格正穩(wěn)定地下降，但PLC的發(fā)明者，Richard E. Morley，認為PLC市場是一個40億的行業(yè)。 尤其，在PLC程序設計過程中的實際問題是消除軟件錯誤并且降低舊的梯形邏輯程序的維修費。雖然PLC的硬件

34、成本正在連續(xù)下降，降低梯形邏輯的掃描時間仍然是工業(yè)應用中面臨的一個問題，以便低成本的PLC能被使用。通常，在產(chǎn)生PLC過程中的生產(chǎn)力比其他領域低，例如，VLSI設計，有高效率的計算機輔助設計工具?，F(xiàn)有的軟件工程方法學對基于PLC的軟件設計不一定適用，因為PLC語言需要同時考慮硬件和軟件。所以現(xiàn)在的軟件工程方法學對建立PLC的軟件設計不是必然可用的。在許多工業(yè)設計應用中，超過50%的人力被預定為測試和檢查PLC程序錯誤。 另外，

35、當今的基于PLC的控制系統(tǒng)沒有被正確的用于支持日益增多的對制造</p><p><b>　　2 目標和意義</b></p><p>　　這篇文章的目標是PLC發(fā)展為一種系統(tǒng)的軟件設計方法學。設計方法學包括基于狀態(tài)轉移模型的高階層的描述，如離散系統(tǒng)，一個梯形程序的自動化控制系統(tǒng)，而且提供指導達成一個成功的設計。這個課題的結果將尋找到在管理控制軟件開發(fā)過程中的錯誤，也就是

36、說，減少經(jīng)過模組化程序和調(diào)試時間和他們的變化，增加自動化系統(tǒng)的靈活性和促成軟件可復用性。目標是克服單個軟件開發(fā)者的經(jīng)驗的現(xiàn)行程序規(guī)劃策略的缺點。</p><p>　　設計PLC軟件的有效方法能克服在生產(chǎn)控制系統(tǒng)的程序設計傳統(tǒng)的方式里的缺點，并且能夠在工業(yè)生產(chǎn)中有廣泛的應用。自動化控制系統(tǒng)被形式語言做模型，相等的狀態(tài)機可能被分析是否達到被要求的目標。第二狀態(tài)機描述提供一個結構化表示法傳達合乎邏輯的需求和約束，像是詳

37、細的安全定則。第三，明確的控制系統(tǒng)設計結果有助于自動的代碼產(chǎn)生。生產(chǎn)可運行的邏輯控制器上的控制軟件能降低軟件程序設計研制時間和人工成本。</p><p>　　（1）用戶驅動的制造業(yè) </p><p>　　在現(xiàn)代生產(chǎn)過程中，系統(tǒng)以產(chǎn)品和生產(chǎn)流程革新為特點，因此必須對改變系統(tǒng)要求迅速反應。主要的挑戰(zhàn)是提供技術以便在變更需要和新的機會之后節(jié)儉重新配置自動化控制系統(tǒng)。設計和操作的知識可能被使

38、用，因此，在工業(yè)實踐過程中給予了重要的競爭優(yōu)勢。</p><p>　?。?）設計的自動化和軟件的高質量</p><p>　　研究已經(jīng)顯示，在自動化系統(tǒng)過程中的程序設計方法沒能與計算機資源的迅速增加相配合。例如，PLC的程序設計仍然是用梯形邏輯圖解依賴一種常規(guī)程序風格。因此，延遲和資源是制造業(yè)發(fā)展的一塊主要的絆路石。測試和出錯超過PLC程序設計被分派的50%的人力。標準[IEC60848，1

39、999；IEC611313，1993；IEC61499，1998；ISO15745-1，1999]已經(jīng)成為固定并且廣泛使用的最新型的設計方法，但是他們通常不能參加發(fā)展有效率的程序和系統(tǒng)的設計知識。</p><p>　　系統(tǒng)的方法將通過使用現(xiàn)有的新軟件增加設計自動化的水平，并且提供方法使大規(guī)模系統(tǒng)設計容易。而且，它將會改良軟件質量和可靠度，特別是危險的環(huán)境，例如飛機場控制和鐵路。</p><p&

40、gt;<b>　?。?）系統(tǒng)的復雜性</b></p><p>　　軟件產(chǎn)業(yè)被認為是一個績效析構函數(shù)的產(chǎn)生器。硬件價格的下降損壞了軟件性能的需要和效率。結果是龐大的低效率軟件代碼在速度上超過了硬件的性能。第二，軟件到了難以控制大小的復雜性；軟件重新設計和維護在現(xiàn)代化的自動化系統(tǒng)中幾乎變得不可能。特別地，PLC程序已經(jīng)在25年以前從一個電耦程序編碼行進展到有輸入/輸出點的一個相似的數(shù)以千計的編碼

41、行。例如在增加安全放火墻上，現(xiàn)代自動化系統(tǒng)的靈活性給予復雜性計劃設計過程。從而，軟件的生命周期費用是永久增長總費用的一小部分。這些費用的80%～90%作為軟件的維護，調(diào)整，適應和擴大滿足不斷變化的需求。</p><p><b>　　（4）設計理論發(fā)展</b></p><p>　　如今，大多數(shù)的設計研究的主要焦點以機械或電氣產(chǎn)品為基礎。被計劃研究的副產(chǎn)品之一將提高我們對

42、基本設計理論和方法學的理解，通過把它擴大到工程系統(tǒng)設計的領域。大規(guī)模和復雜系統(tǒng)的設計理論還沒被完全發(fā)展。尤其，怎樣簡化一項錯綜復雜或者復雜的設計工作的問題還沒被以科學方式處理。而且，在設計理論和最新epistemological正式表現(xiàn)在計算機科學和運籌學的結果之間，例如模型化系統(tǒng)分離事件，將推動以后的工程設計。</p><p>　?。?）在合乎邏輯的硬件設計過程中的應用</p><p>