在自動(dòng)化過程中的可編程序邏輯控制器

畢業(yè)設(shè)計(jì)外文資料翻譯 題 目在自動(dòng)化過程中的可編程序邏輯控制器 學(xué) 院 機(jī)電與車輛工程學(xué)院 專 業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 班 級(jí) 學(xué) 生 學(xué) 號(hào) 指導(dǎo)教師 二0一四年三月一日 4th International DAAAM Conference "INDUSTRIAL ENGINEERING - INNOVATION AS COMPETITIVE EDGE FOR SME" 29 - 30th April 2004, Tallinn, Estonia PROGRAMMABLE LOGIC CONTROLLERS IN PROCESS AUTOMATION Ahti Mikkor, Lembit Roosimolder Department of Product Development, Institute of Machinery, Tallinn Technical University, Ehitajate tee 5, 19086 Tallinn, Estonia ahti.mikkor@ Abstract: Nowadays, control problems are solved using operating components from a wide variety of technologies: electronics, hydraulics, pneumatics and mechanics. Functio-nality, reliability and price of the controlled system are deter-mined by the quality of the solution made. The paper concentrates on practical use of programmable logic controllers (PLC) that is based on the five years project development experience in this area. Successful solutions and problems are under focus. Specific hardware, controller programming problems, data/signals exchange and human machine interfaces are considered. As a result the method for selecting programmable controllers according to specific needs is developed. Practical suggestions, possible hazards and warnings are proposed that could help to avoid mistakes. Key words: programmable controllers, PLC, automation, automation systems, process automation. 1. INTRODUCTION Modern machinery consists of both mechanical and electronic parts. Overall functionality is determined by "balance" between these components. Initial planning and solution selection plays critical role in final result. In control methods the selection has to be made between relay-based circuits, special devices, programmable logic controllers (PLC) and new development electronics. This article is concentrated on PLC-s and experience that has collected over 5-year practical work with PLC-s. Strong and weak sides, positive and negative practices are discussed. Suggestions weather to use programmable controllers or not have been formed to help decision making. The most important decision in planning PLC-based system is selecting processor type. Mistakes mean extra costs for modifications or even need for completely new devices. The most common error is overestimating programming possibilities of small-sized processors. There are several methods for selecting PLC. Unfortunately most of them focus on electrical side of PLC-s and maximum count of signals allowed. They don’t involve analysis to determine possible special needs for user program or communications. Based on several existing methods, practical experience and future trends a new method for selecting PLC was developed. Ahti Mikkor has gained his experience by taking part in more than 15 big-scale automation projects. These projects include development of power consumption monitoring system in AS Kunda Nordic Cement factory, renewing testing rig for flowmeters, building Ahtme powerplant turbine safety systems, water treatment plants in towns Rakvere and Polva, waste water treatment plant in town Jogeva and development of monitoring system for central heating network in Tartu. 2. PROS AND CONS IN USING PROGRAMMABLE LOGIC CONTROLLERS 2.1 Positive arguments The main advantage that programmable controllers provide is flexibility (Jack, 2003). Behaviour of the system can be easily changed via program without any other alterations. Special devices for example make any changes in control algorithm very hard to implement. Flexibility makes PLC-s well suitable for frequently changed applications, for example in robotics. In PLC-s the relations between inputs and outputs are determined by user program. By using advanced programming technologies it is much easier to implement complex control algorithms than in any hard-wired solutions. It makes PLC-s very competitive for complex tasks, for example in controlling chemical processes. Special modules allow vast amount of different signals to be connected to the PLC system. Use of PLC-s should be considered in applications that require some “ specialinput or output signals. Typical example would be positioning using reference data from high-speed input. Typically PC visualization software packages are made for PLC-s. Some special devices have also PC software packages. Wide range of communication options between PLC-s makes it possible to gather all information from field devices into one central control point. Communication lines between PLC-s allow using information collected from other parts of the system in local process control. Modern communication technologies enable remote diagnostics and configuration (Jack, 2003). These two significantly reduce overall maintenance costs of the system. 2.2 Negative arguments Programmable controllers are not equipped with enough memory to store big amounts of data. Although future trends show growth in PLC memory sizes, special devices (recorders) are still better suited for standalone datalogging applications. For networked solutions there is possibility to use visualization software packages together with PLC-s to archive collected data in any database format necessary. If~ -2 - logged data amounts are small or there are also control functions included, it’s reasonable to still use PLC-s. About visualization software packages it’s good to know that in standard versions most of them do not support offline recording so that after communication breakdown it is not possible to acquire data backwards from PLC. Modern communication options for PLC-s include standard protocols for example Ethernet. It is tempting to use existing office networks also as data carrier for automation system communications. Time has shown that it is better practice to keep these two separated if there is a need for constant online communication. Hardly traceable temporal network overloads can cause problems also in automation system communications. All PLC-s need be programmed. All programming works include risk for accidental errors in control algorithm. Special devices are well tested and generally free of this kind of problems. If available, it’s economically thoughtful to use special devices. Safety applications that require highest degree of reliability should contain simplest devices and circuits possible. There is a rule that every new link in chain decreases overall reliability. In small applications it’s often cost saving to use relay-based circuits instead of PLC-s. Progress in process automation systems is aiming at so called complete automatiowhen all the human has to do is to enter the parameters of the product wanted and everything else is carried out by machines (Rosin, 2000). Although the destination lies far ahead, trends indicate movement in that direction. Firstly, systems become more and more standardized. Big manufacturers organize their products into families. The aim is to reduce amount of knowledge needed for configuration and maintenance works of different devices from same company. It’s also important that this way built applications are easily expandable. Secondly, importance of communication is rising (Hughes, 2000). There are many reasons, some of more essentials are: ? Better collaboration of different parts of the system. ? Cutting costs on cabling. Less cabling results fall in fault probability, but also increases severity of ones that occur. ? Sensors and actuators can be at long er distances from the processor module than if using conventional methods. ? Increased scalability of the systems. New devices can be added at minimal costs. ? At some cases it is better to make architecture of many small independent modules and network them. This solution enables system to keep working although some parts have failed. ? Communication networks ease fault diagnostics and provide remote management possibilities. Central operating stations can be formed relatively easy. ? Possibility to connect devices form different manufacturers (OPC Foundation, 2003). Third important tendency is spreading use of so called software controllers or Soft PLC-s (Siemens AG, 2003). These are PC software-based solutions that relate with field devices via communication networks. There is no need for processor module, resources of PC are used. Some Soft PLC-s are still formed as processor cards for PC . Reliable communication networks are essential. Soft PLC-s are well suited for data acquisition applications because of data storage possibilities of PC-s. Fourthly, combo-devices (figure 2) that contain both operator panel and medium size processor module gain popularity (Siemens AG, 2002). In this solution possibility of disturbances is low and reuse of some components make whole package cheaper. Fifthly, processor software takes over properties from PC software. Data collected from production can be easily transferred into office applications (Siemens AG, 2000). REFERENCES Hughes, T. A. Programmable Controllers, Third Edition. ISA - The Instrumentation, Systems, and Automation Society, 2000, 334 p. Jack, H. Automating Manufacturing Systems with PLC-s, 828 p., Available: http://claymore.engineer.gvsu.edu/~jackh/books/plcs/pdf/plcbook4_2.pdf, Accessed: 3.10.2003 LOGO! Manual. Siemens AG, 2003, 312 p. OPC Foundation homepage: http://www.opcfoundation.org/, Accessed: 9.11.2003 Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] - in Estonian. Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p. SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p. SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p. SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG 2000, 468 p. 57 4th International DAAAM Conference "INDUSTRIAL ENGINEERING -NNOVATION AS COMPETITIVE EDGE FOR SME" 29 - 30th April 2004, Tallinn, Estonia Ahti Mikkor, Lembit Roosimolder Department of Product Development, Institute of Machinery, Tallinn Technical University, Ehitajate tee 5, 19086 Tallinn, Estonia ahti.mikkor@ 摘 要 現(xiàn)在，控制問題解決了使用操作各種各樣的技術(shù)：電子，液壓，氣動(dòng)和機(jī)械。功能、可靠 性和控制系統(tǒng)的價(jià)格是由方案的質(zhì)量來決定的。 本文主要介紹的可編程邏輯控制器是基于五年項(xiàng)目開發(fā)經(jīng)驗(yàn)得來的。成功的解決方案和問題 正是關(guān)注的焦點(diǎn)。 特定的硬件，控制器編程問題，數(shù)據(jù)/信號(hào)改變和人機(jī)界面，也會(huì)被考慮到。作為一個(gè)結(jié)果，選 擇方法根據(jù)具體的需求可編程控制器的設(shè)計(jì)與開發(fā)。實(shí)用的建議,提出了可能的危害和警告或許 有助于避免犯錯(cuò)誤。 關(guān)鍵詞 可編程控制器PLC自動(dòng)化自動(dòng)化系統(tǒng)過程自動(dòng)化 1簡介 現(xiàn)代機(jī)械包括機(jī)械和電子兩部分。整體功能是由各組件的平衡共同決定的。最初 的計(jì)劃和解決方案的選擇對(duì)最終結(jié)果起至關(guān)重要的作用。 在基于繼電器電路、特殊裝置可編程邏輯控制器(PLC )和新的發(fā)展電子產(chǎn)品等控制方 法之間做出選擇。這篇文章集中在PLC-s和手機(jī)了 5年以上用PLC-s實(shí)際工作的經(jīng)驗(yàn)。 對(duì)強(qiáng)、弱邊，正面和負(fù)面的實(shí)踐進(jìn)行了探討。建議使用可編程控制器而不是已經(jīng)形成 來幫助決策。 在規(guī)劃的最重要的決定是基于PLC系統(tǒng)選擇處理器類型。修正的錯(cuò)誤就是額外 的費(fèi)用甚至需要全新的裝置。最常見的錯(cuò)誤是過高估計(jì)了編程的可能性和小型處理 器。有幾種方法為選擇可編程序控制器(PLC)。不幸的是,他們中的大多數(shù)集中在電氣 的方面PLC-s計(jì)數(shù)信號(hào)和最大允許的信號(hào)。他們不涉及可能的特殊需求的分析來確定 為用戶程序或通訊。 基于現(xiàn)有的幾個(gè)方法、實(shí)踐經(jīng)驗(yàn)和未來的發(fā)展趨勢,提供了一種新的方法選擇可 編程序控制器(PLC)出現(xiàn)了。Mikkor Ahti通過參加超過15個(gè)大型自動(dòng)化工程取得了 他的經(jīng)驗(yàn)。這些項(xiàng)目包括發(fā)展電力消費(fèi)市場的不斷監(jiān)測系統(tǒng)在北歐水泥廠、更新測試 試驗(yàn)臺(tái)為流量計(jì)、建筑Ahtme比作汽輪機(jī)安全系統(tǒng)、水處理設(shè)備，在波瓦拉克維里 城鎮(zhèn)污水處理裝置和在塔爾圖中央供暖網(wǎng)絡(luò)監(jiān)控系統(tǒng)的發(fā)展。 2使用可編程控制器的優(yōu)點(diǎn)和缺點(diǎn) 2.1積極的爭論 可編程控制器提供的主要優(yōu)勢是其靈活性。這是由于系統(tǒng)可以通過程序輕易的改 變而不是其他任何選擇。特殊裝置為例做任何變化在控制算法很難實(shí)施。靈活性使 PLC-s很適合頻繁改變應(yīng)用程序，例如在機(jī)器人學(xué)。在PLC-s輸入和輸出之間的關(guān)系是 由用戶程序。通過采用先進(jìn)的編程技術(shù)，它是比任何天生的解決方案都非常容易實(shí)現(xiàn) 復(fù)雜的控制算法。它使PLC-s非常激烈復(fù)雜的任務(wù)，例如在控制化學(xué)反應(yīng)過程。特殊模 塊允許大量的不同信號(hào)連接到PLC控制系統(tǒng)。使用中應(yīng)考慮的PLC-s應(yīng)用程序需要一些 “特別”的輸入或輸出信號(hào)。典型的例子就是定位以參考數(shù)據(jù)，從高速輸入。 典型的PC可視化軟件是PLC-s,也有一些特殊裝置PC套裝軟體。在PLC-s之間有廣 泛的通訊選擇使人們有可能從現(xiàn)場設(shè)備到一個(gè)中央控制的觀點(diǎn)收集所有的信息?，F(xiàn)代 通信技術(shù)能夠使遠(yuǎn)程診斷和配置(杰克,2003)。這兩個(gè)顯著地降低系統(tǒng)的整體維護(hù)成 本。 2.2消極的爭論 可編程控制器沒有足夠的內(nèi)存來存儲(chǔ)大量的數(shù)據(jù)。盡管未來趨勢顯示PLC內(nèi)存的 增長，但是特殊裝置可編程序控制器(PLC)里記憶體的大小(錄音機(jī))仍然更好地適用 于獨(dú)立的應(yīng)用程序。對(duì)于網(wǎng)絡(luò)解決方案有可能使用可視化軟件一起，以達(dá)到預(yù)期PLC-s 所收集的數(shù)據(jù)在任何數(shù)據(jù)庫格式是很必要的。如果記錄的數(shù)據(jù)量是小的或也有控制功 能包括，可以合理的PLC-s仍在使用。關(guān)于可視化軟件令人改性的是，在標(biāo)準(zhǔn)版本下， 大多數(shù)不支持離線的記錄,在溝通是白的情況下不肯能獲得從PLC返回的數(shù)據(jù)。 現(xiàn)代通信選項(xiàng)包括標(biāo)準(zhǔn)協(xié)議PLC-s,例如以太網(wǎng)。人們傾向于使用現(xiàn)有的辦公室網(wǎng) 絡(luò)也為數(shù)據(jù)載體，自動(dòng)化系統(tǒng)的通信。時(shí)間已經(jīng)表明它是更好的方法把這些兩相分離 的不斷的進(jìn)行網(wǎng)絡(luò)交流。在自動(dòng)化系統(tǒng)的通信中，幾乎有可追溯性的顳網(wǎng)絡(luò)超負(fù)荷會(huì) 導(dǎo)致一些問題。所有PLC-s都需要被編程。所有的編程程序在風(fēng)險(xiǎn)控制中包含偶然誤 差。特殊裝置，通常能夠很好的檢測并處理這類問題。如果有的話，使用特殊裝置是經(jīng) 濟(jì)的。要求最高程度的可靠性的安全應(yīng)用應(yīng)包含簡單的裝置和可能的電路。有 條規(guī) -6 - 定。每一個(gè)環(huán)節(jié)降低總體可靠性鏈。在小型的應(yīng)用中，使用基于繼電器的電路而不是 PLC-s是很節(jié)約成本的。 3未來趨勢 過程自動(dòng)化系統(tǒng)的進(jìn)步是針對(duì)所謂的完全自動(dòng)化，所有人要做的是輸入所需要產(chǎn) 品的數(shù)據(jù),然后所有的工作有機(jī)器完成（松香,2000年）。盡管目標(biāo)很遙遠(yuǎn)，但是趨勢 決定運(yùn)動(dòng)的方向。 首先，系統(tǒng)變得越來越標(biāo)準(zhǔn)化。大型制造商組織他們的產(chǎn)品家族化。其目的是減 少所需數(shù)量的知識(shí)結(jié)構(gòu)和維修工程的不同設(shè)備來自同一家公司。也是很重要的應(yīng)用， 該方法建立容易擴(kuò)展。 其次，交流的重要性日益突出（休斯,2000年）。有很多原因,更多的一些要點(diǎn)： -系統(tǒng)的各個(gè)部分更好的合作。 ?減少布線成本。減少布線在故障上的的概率，但也增加了那些發(fā)生的嚴(yán)重程度。 -傳感器與執(zhí)行器，可以在更遠(yuǎn)的地方比來自處理器模塊使用傳統(tǒng)的方法。 ?增加了系統(tǒng)的可擴(kuò)展性。新的設(shè)備可以被添加在最小的成本。 ?在某些情況下，是更好的使建筑的許多小的獨(dú)立的模塊和網(wǎng)絡(luò)。這種方法能系統(tǒng) 來保護(hù)工作雖然有些部分都失敗了。在某些情況下，是更好的使建筑的許多小的獨(dú)立 的模塊和網(wǎng)絡(luò)。這種方法能系統(tǒng)來保護(hù)工作雖然有些部分都失敗了。 ?通訊網(wǎng)絡(luò)的故障診斷，提供輕松遠(yuǎn)程管理的可能性。中央操作站，可以形成相對(duì) 容易了。 ?連接裝置可能出自不同的廠家（OPC基金會(huì),2003年）。 第三個(gè)重要趨勢是傳播使用所謂的軟件或軟PLC-s控制器（西門子集團(tuán),2003）。 這些基于軟件的解決方案,是通過網(wǎng)絡(luò)使PC機(jī)和現(xiàn)場設(shè)備相連接。沒有必要處理模 塊,PC機(jī)的資源是被使用的。一些軟PLC-s仍然形成了以處理器為PC卡片。可靠的 通信網(wǎng)絡(luò)是至關(guān)重要的。軟PLC-s非常適合用于數(shù)據(jù)采集應(yīng)用，這是由于PC-s數(shù)據(jù)儲(chǔ) 存。 第四，組合裝置既包含操作員面板和中等大小的處理器模塊獲得聲望（西門子公 司,2002年）。在這個(gè)方案的可能性低和重用的干擾的一些組件使整個(gè)包裝更便宜。 最后，軟件處理器接管PC軟件的性能。從生產(chǎn)中收集的數(shù)據(jù)就可以很容易地傳 輸?shù)睫k公應(yīng)用軟件（西門子公司,2000年）。 參考文獻(xiàn) 休斯，T.A.可編程控制器第三版ISA——儀表儀器，系統(tǒng)和自動(dòng)化社會(huì)2000，p334 杰克，H應(yīng)用PLC-s的自動(dòng)化制造系統(tǒng)p828,可獲得： http://claymore.engineer.gvsu.edu/~jackh/books/plcs/pdf/plcbook4_2.pdf, 2003.3.10 下載 商標(biāo)！西門子手冊，2003，p214 主頁：http://www.opcfoundation.org/, 2003.9.11 下載 松香，A.可編程控制器Simatic塔林，TTU.2000,p120 ［碩士論文］-愛沙尼亞語 伯格，H SIMATIC自動(dòng)化.西門子，2003，p214 使用7v5.2的SIMATIC編程 西門子手冊，2003, p417 s7 - 200系列可編程控制器SIMATIC系統(tǒng) 西門子手冊，2003，p474 介紹SIMATIC HMI WinCC配置手冊 第一、二、三冊 西門子手冊，2000，p334