電氣工程自動化外文翻譯外文文獻(xiàn)英文文獻(xiàn)PLC未來發(fā)展趨勢

1、 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 roosimölderdepartment of product development, institute of machinery, tal

2、linn 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 sy

3、stem 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 prog

4、ramming 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:

5、 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 rol

6、e 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. stron

7、g 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 e

8、ven 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 dont involve analysis

9、 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 p

10、rojects 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 põlva, waste water treatment plant in town jõgeva and dev

11、elopment 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 a

12、ny 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 usi

13、ng 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

14、 the plc system. use of plc-s should be considered in applications that require some “special” input 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

15、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 comm

16、unication 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 growt

17、h 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 logged data amoun

18、ts are small or there are also control functions included, its reasonable to still use plc-s. about visualization software packages its 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 backwa

19、rds 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

20、 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 t

21、his kind of problems. if available, its 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 applicati

22、ons its often cost saving to use relay-based circuits instead of plc-s. 3. future trends progress in process automation systems is aiming at so called complete automation when all the human has to do is to enter the parameters of the product wanted and everything else is carried out by machines (ros

23、in, 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 diff

24、erent devices from same company. its 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 cab

25、ling. less cabling results fall in fault probability, but also increases severity of ones that occur. sensors and actuators can be at longer distances from the processor module than if using conventional methods. increased scalability of the systems. new devices can be added at minimal costs. at som

26、e 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 for

27、med 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 communicatio

28、n 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 (figure 1). reliable communication networks are essential. soft plc-s are well suited for data acquisition applications because of data storage possibilities of pc-

29、s. figure 1. siemens simatic winac slot plc 412fourthly, 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. figure

30、2. combo device siemens simatic c7-613 fifthly, processor software takes over properties from pc software. data collected from production can be easily transferred into office applications (siemens ag, 2000). 4. method for selecting programmable controller a method for forming an application specifi

31、c list of required properties for selecting programmable controller was developed. there are nine criterions and the results are presented in table 1. selection is made by comparing results table with controllers technical data. following is short description of every criteria involved. nature of so

32、lution determines weather it is expanding of old system or completely new development. in first case the architecture of system and hardware requirements are limited by already existing solution. using hardware from same company makes servicing easier and avoids integration problems that would occur

33、 when using products form different manufacturers. for example many hardware producers integrate their own specific communication interfaces directly into processor module and for every universal protocol a special module is needed (siemens ag, 2003). it is also possible to reduce spare part stock a

34、mounts when using same type hardware all over the system. maximum number of electrical inputs-outputs allowed is classical criteria to determine processor class. if complex control algorithms and non-standard functions are needed, its not the most important parameter any more. generally it is money

35、saving to use one bigger processor module for input-output signals that originate from nearby locations than several smaller ones. in this case there will be no need for communication network and programming will be easier too. special signals and modules are usually available for medium and large c

36、ontroller families only. many microcontrollers do not even have possibility to add analogue output (siemens ag, 2003). in some cases using special modules is the only way, in other ones (positioning) it is just an opportunity to save money. layouts of sensors and actuators can be very different, som

37、etimes the sensors are located several kilometres away from the actuator (pumping liquids in long pipes). in this case special communication network (profibus, as-inteface) might be the only solution. if not, it can at least save costs by reducing cabling works. not all programmable controllers have

38、 interfaces for communication protocols. properties of processor have important role in complex applications. most common problem is lack of programming memory, sometimes also data memory. memory requirements can be estimated by number of input and output signals. but in practice 100 digital input-o

39、utput points system often has 3 times smaller program than 10 digital input-output points system. the only way to estimate program size exactly is using previous experience. program specialities include special program functions needed. different areas of applications have some typically used functi

40、ons, for example temperature control in building automation. programming is much simpler if these functions are already built into system software of processor. in process automation 2 digital output (up-down) closed loop pid regulation is quite often used. it might be a surprise but its not include

41、d in most of the microcontrollers (siemens ag, 2003) and for average programmer its too complicated task to create his own regulator using standard functions. basically there are 2 solutions: either to avoid this construction or to use applicable controller. table 1. table for method results communi

42、cation is becoming more important in nowadays automation systems. in some cases non-standardised devices as barcode readers or electronic weights have to be included into the system. then its vital to have functions for protocol programming (freeport programming). standardised protocols demand exist

43、ence of specific modules. working conditions can usually be overcome by using special cabinets, but there are also specific series of programmable controllers that have improved resistance for electromagnetic disturbances, humidity and vibrations. in very dusty environments all cooling ventilators h

44、ave to be equipped withfilters.5. conclusions main benefits of programmable controllers are: flexibility communication possibilities realisation of complex control algorithms reliability alternative solutions should be considered if: system is very simple special devices are available data recording

45、 is necessary initial selection of appropriate solution and hardware has great influence on final result. mistakes in this step significantly increase overall budget of project as some programs might have to be changed and some hardware replaced. based on his practical experience the author has form

46、ed a method for selecting programmable controller. it has 9 criterias: nature of solution (new or existing) maximum number of electrical inputs-outputs allowed (digital, analogue, inputs, outputs) need for special modules (high-speed digital outputs) layout of sensors and actuators (local or periphe

47、ry) properties of processor (program and data memory) program specialities (special functions) communication needs (profibus, ascii) working conditions (humidity, temperature, vibration, dust) method is not guaranteed to always point out the best selection, but using it certainly avoids mistakes. 6.

48、 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: /jackh/books/plcs/pdf/plcbook4_2.pdf, accessed: 3.10.2003

49、 logo! manual. siemens ag, 2003, 312 p. opc foundation homepage: /, 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 wit

50、h 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. 摘自可編程控制器在過程自動化中的應(yīng)用ahti mikkor,lembit roosimolderdepartment of product development,institute

51、of machinery,tallinn technical university,ehitajate tee 5,19086tallinn.摘要：目前，控制問題解決了各種各樣的技術(shù)操作部分：電子，液壓，氣動和機(jī)械。函數(shù)- nality，可靠性和控制系統(tǒng)的價格是阻止開發(fā)的理由。本文集中于可編程邏輯控制器（plc），以五年在這方面的發(fā)展經(jīng)驗(yàn)為基礎(chǔ)。成功的解決方案是問題重點(diǎn)。具體的硬件，控制器編程的問題、數(shù)據(jù)/信號的交換和人機(jī)界面進(jìn)行審議。實(shí)際的建議，需要根據(jù)具體的方法來開發(fā)可編程控制器。對于可能出現(xiàn)的錯誤和警告，提出可以幫助避免方法。關(guān)鍵詞：可編程控制器、自動化、自動化系統(tǒng)、過程自動化1引言現(xiàn)代

52、的機(jī)器包括電子和機(jī)械兩部分。平衡兩方面因素，初步規(guī)劃和方案選擇對最終結(jié)果起著至關(guān)重要的作用。在控制方法的選擇，繼電器，專用設(shè)備，可編程邏輯控制器（plc）和電子制造技術(shù)的發(fā)展。這篇文章是基于plc集中- s的經(jīng)驗(yàn)，擁有超過5年的plc - s的實(shí)際工作經(jīng)驗(yàn)中收集的。雙方強(qiáng)弱，積極和消極的做法進(jìn)行了討論。建議使用可編程控制器幫助解決。在規(guī)劃基于plc系統(tǒng)中最重要的決定是選擇處理器類型。誤區(qū)是意味著修改額外費(fèi)用或擴(kuò)展完全新設(shè)備的需要。最常見的錯誤是高估小型處理器編程的可能性。有選擇plc的幾種方法。不幸的是，他們大多集中在電氣方面的plc - s和允許的最大計數(shù)信號。他們不涉及分析，以確定用戶程序

53、或通信可能的特殊需要。基于幾個現(xiàn)有的方法，實(shí)踐經(jīng)驗(yàn)和未來趨勢的選擇為開plc的開發(fā)提供新的方法。阿赫蒂瓦爾mikkor已獲得通過采取在超過15個大范圍的自動化項目的一部分，以他的經(jīng)驗(yàn)，這些項目包括電力消耗在as昆達(dá)北歐水泥工廠監(jiān)控系統(tǒng)的開發(fā)，更新測試流量計鉆機(jī)，建設(shè)城鎮(zhèn)rakvere和普亞，污水處理廠在城里jogeva和發(fā)展動力渦輪安全系統(tǒng)，污水處理廠在塔爾圖監(jiān)測網(wǎng)絡(luò)系統(tǒng)的集中供熱。2可編程控制器在投票站的使用2.1正面論據(jù)主要優(yōu)勢是靈活性提供可編程控制器（杰克，2003年）該系統(tǒng)的行為可以很容易地通過計劃，沒有任何其他的改動。例如特殊裝置使控制算法很難實(shí)現(xiàn)任何改變。靈活性使得plc的- s經(jīng)

54、常更換適合應(yīng)用在機(jī)器人的例子。在plc - s的投入和產(chǎn)出之間的關(guān)系是由用戶程序決定。通過使用先進(jìn)的編程技術(shù)比任何硬連接解決方案容易得多，以實(shí)現(xiàn)復(fù)雜的控制算法。它使plc在復(fù)雜的任務(wù)很有競爭力。例如，在控制化學(xué)過程，特別模塊，讓大量不同的信號被連接到plc系統(tǒng)。plc - s的使用，應(yīng)考慮應(yīng)用，需要一些“特殊”的輸入或輸出信號。典型的例子是利用定位高速輸入?yún)⒖嫉臄?shù)據(jù)。通常個人電腦的可視化軟件是由可編程序控制器plc- s控制，也有一些特殊設(shè)備的pc軟件包。寬的plc - s的通信選擇范圍使得它能夠收集到一個中央控制點(diǎn)。搜集現(xiàn)場的所有設(shè)備的信息。窄的plc - s的通訊線路允許使用從本地過程控制

55、系統(tǒng)的其他部分中收集信息。現(xiàn)代通訊技術(shù)實(shí)現(xiàn)遠(yuǎn)程診斷和配置（杰克，2003年）。這兩方面顯著降低了系統(tǒng)的總體維護(hù)成本。2.2沒有配備足夠的內(nèi)存來存儲數(shù)據(jù)雖然未來的趨勢在plc內(nèi)存大小，（錄像機(jī)）專用設(shè)備的增長仍然是更適合于獨(dú)立的數(shù)據(jù)記錄應(yīng)用。對于網(wǎng)絡(luò)解決方案，有可能使用可視化軟件包一起與plc - s到存檔于任何數(shù)據(jù)庫格式收集必要的數(shù)據(jù)。如果記錄的數(shù)據(jù)量小或者有控制功能也包括在內(nèi)，采用plc - s是合理的。關(guān)于它的可視化軟件，知道他們在標(biāo)準(zhǔn)版本的大多數(shù)不支持脫機(jī)錄音通訊故障后，使我們無法獲得向后從plc的數(shù)據(jù)。對plc的現(xiàn)代通訊選項包括，例如以太網(wǎng)標(biāo)準(zhǔn)協(xié)議。人們很容易用數(shù)據(jù)自動化系統(tǒng)的通信運(yùn)營

56、商中獲得。時間已經(jīng)證明，最好的做法是保持這兩方面分離的，如果有一個經(jīng)常上網(wǎng)的通信需求。幾乎沒有時間可追溯網(wǎng)絡(luò)超載問題，也可能在自動化系統(tǒng)的通信。所有的plc - s的需要進(jìn)行編程，所有的編程作品包括在控制算法和意外錯誤的風(fēng)險。特種設(shè)備是行之有效的，并且通常解決這類問題的。如果有的話，它是經(jīng)濟(jì)的使用特殊設(shè)備。安全應(yīng)用需要最高的可靠性程度，應(yīng)該包含最簡單的設(shè)備和電路。有一個規(guī)則，每一個鏈的新環(huán)節(jié)可能降低整體的可靠性。在小型系統(tǒng)應(yīng)用中，經(jīng)常節(jié)省成本使用中繼電路，而不是使用plc的- s的。3今后的趨勢過程自動化系統(tǒng)的進(jìn)展是針對所謂的完全自動化，所有的人所要做的就是進(jìn)入該產(chǎn)品的參數(shù)和其他一切工作由機(jī)器

57、（松香，2000年）協(xié)調(diào)。雖然目標(biāo)遙遙領(lǐng)先，表明在這個方向的趨勢運(yùn)動。首先，系統(tǒng)變得越來越規(guī)范。從大型制造商組織到家庭的產(chǎn)品。其目的是減少對來自同一公司不同的設(shè)備配置和維護(hù)工作所需的知識量。同樣重要的是這種方式構(gòu)建的應(yīng)用程序很容易擴(kuò)展。其次，溝通的重要性正在上升（休斯，2000）。有很多原因，更多的要領(lǐng)有：更好的系統(tǒng)是不同部分的合作。 降低成本的布線。減布線結(jié)果增加了故障率，也增加了那些發(fā)生的嚴(yán)重程度。 傳感器與驅(qū)動器可以在從傳統(tǒng)方法相比，如果使用的處理器覆蓋更長的距離。 提高了系統(tǒng)的可擴(kuò)展性。在增加新設(shè)備時以最低的成本。 在某些情況下，最好是讓許多小型的獨(dú)立模塊和網(wǎng)絡(luò)架構(gòu)。該解決方案使系統(tǒng)繼

58、續(xù)工作，盡管一些地區(qū)已經(jīng)失敗。 方便的通信網(wǎng)絡(luò)故障診斷為遠(yuǎn)程管理提供了可能性。中央操作站，可形成相對容易。 可將設(shè)備連接形式（opc基金會，2003）不同的生產(chǎn)廠家。第三個重要趨勢是散布所謂的軟件控制器或軟plc - s的（西門子股份公司，2003年）的使用。這些都是電腦軟件為基礎(chǔ)的解決方案，通過通信網(wǎng)絡(luò)與現(xiàn)場設(shè)備。有沒有需要的處理器模塊，使用的pc資源。有些軟plc - s仍然為pc處理器卡（圖1）?？煽康耐ㄐ啪W(wǎng)絡(luò)是必不可少的。軟plc - s是非常適合于個人電腦的數(shù)據(jù)存儲數(shù)據(jù)采集應(yīng)用的。圖1。西門子的simatic winac插槽式plc 412第四，組合裝置（圖2）同時包含操作員面板和中等規(guī)模的處理器模塊得到普及（西門子股份公司，2002）。這個解決方案的可能性很低，一些組件的重用使整個包便宜。西門子simatic組合設(shè)備的c7 613第五，處理器軟件接管從pc軟件性質(zhì)。收集的數(shù)據(jù)可以很容易地從生產(chǎn)到office應(yīng)用程序轉(zhuǎn)移（西門子股份公司，2000）。4 可編程