plc外文翻譯---基于plc的教育教學(xué)材料的虛擬實(shí)驗(yàn)系統(tǒng)的研究

1、<p>　　浙江工業(yè)大學(xué)教科學(xué)院</p><p>　　畢業(yè)設(shè)計(jì)外文資料翻譯</p><p>　　設(shè)計(jì)題目： 龍門刨床刨臺(tái)運(yùn)動(dòng)模擬器的設(shè)計(jì) </p><p>　　學(xué)生姓名： 　 </p><p>　　學(xué) 號(hào)：

2、 </p><p>　　專 業(yè)： </p><p>　　外文出處：Communications in Computer and Information Science, 1, Volume 225, Applied Informatics and Communication, Par

3、t 2, Pages 479-486</p><p>　　指導(dǎo)教師： 　 </p><p>　　2012年 2 月 12 日</p><p>　　The Design and Application of Sewage Treatment</p><p>　　Automat

4、ion System Based on S7-300 PLC</p><p>　　Abstract. For the demand of domestic sewage treatment in county-level city, a plan of Distributed Control System in municipal wastewater treatment automation system is

5、 proposed. The main function of which is to supervisory control each sub-system of municipal wastewater treatment via the configuration software WinCC, Siemens S7-300 PLC. The feature of the system is mainly as follows,

6、collection of PLC data, protocol conversion, the transmission of data through fiber, the realization of projects </p><p>　　Keywords: sewage treatment, Distributed Control System, Siemens S7-300 PLC, WinCC C

7、onfiguration software.</p><p>　　Introduction</p><p>　　Along with the rapid development of economy in China, environmental protection has been a prominent issue. Sewage Treatment is one of the mo

8、st important parts of environmental protection. As the computer technology and sewage treatment technology developed rapidly, it is necessary to monitor the wastewater treatment process with advanced control technology a

9、nd equipment.</p><p>　　The sewage treatment project of Inner Mongolian Huhhot Tumd Left Banner is the typical project among the county-level city of Hohhot, using Cyclic Activated Sludge System (CASS) to tre

10、at wastewater. For this project, we designed a DCS system, whose control system is Siemens S7-300 PLC and monitoring software is Siemens WinCC 6.2.</p><p>　　CASS Process</p><p>　　CASS biochemica

11、l treatment system is a complex system of multi-parameter (such as liquid level, water quality, flow rate, pressure, etc.), multi-tasking (such as water-in, aeration, sedimentation, drainage, etc.), multi-equipment (such

12、 as water decanter, blower, regulator etc.). It is the core of the whole biochemical disposal system. The main reaction zone of CASS pool works according to “aeration, idle, sedimentation, and decanter” cycle procedures.

13、 Among them, the control of dissolved oxygen</p><p>　　The Structure of Control System</p><p>　　The structure of automatic sewage treatment control system is centralized management and decentral

14、ized control. The control system employs the control method combined with remote automatic control, remote manual control and field automatic control.</p><p>　　In order to ensure sewage treatment systems wel

15、l running, the master station and slave station of PLC are independent. If one of the sub-systems breaks down, it will not affect the normal running of other system devices. Even if the whole control system malfunctions,

16、 it also can adjust itself to field manual control mode in time to ensure the normal operation of the sewage treatment system. The PC in the central control room uses the model of dual-redundant to realize real-time moni

17、toring. Two s</p><p>　　Data Communication</p><p>　　S7 series PLC communications network mainly includes the following: multi-point interface (MPI) protocol of data communi cations, PROFIBUS, ind

18、ustrial Ethernet, point-to-point connections, through AS-I process of communication. This project has PROFIBUS, used in industrial Ethernet, point-to-point connections.</p><p>　　The communication between S7-

19、300 and WinCC</p><p>　　PLC and PC communicate with each other through industrial Ethernet, PLC transmit the data of real-time production to the real-time database of configuration software of PC via optical

20、fiber. PC can monitor the field device from far away. Because the PLC selected in this system is CPU 315-2PN/DP, which has integrated PROFINET interface. Communication between S7-300 and WINCC uses TCP/IP network protoco

21、l. TCP/IP network protocol is a de facto standard about communication protocol in IT services. A</p><p>　　The Communication between master station and slave station of PLC</p><p>　　PLC master st

22、ation uses Siemens S7-300 PLC. The PLC of ClO2 workshop uses Siemens S7-200 PLC; Communication between master station and slave station of PLC uses Profibus. Profibus, is internationalized and open, do not depend on the

23、standard fieldbus of equipment manufacturer. It is a fieldbus which is used for control of factory automation workshop-level and data communications, and control of field device-level. The transmission speed of Profibus

24、is at 9600 bauds ~1.2×107 bauds, and when the m</p><p>　　The communication between PLC and power equipment</p><p>　　According to the design requirements, the communication between PLC and p

25、ower equipment need to be established, for the current, voltage and power in the power supply system should be monitored. Siemens PLC make the point-to-point communication link with the power equipment through the commun

26、ication module CP341. The power equipment provides RS485 communication interface in half-duplex asynchronous serial communication, and uses MODBUS RTU communication protocol. </p><p>　　MODBUS protocol is one

27、 of the network protocols in the industrial control unit. The control equipments produced by different manufacturers can be linked as industrial network by MODBUS protocol, and that equipments linked in the different net

28、works can make the data communication. The MODBUS network can connect multiple equipments on one line, and each of the equipments can set communication address itself. Each controller can distinguish the devices by the a

29、ddress. Also, it decides what to do wi</p><p>　　Siemens S7-300 Hardware</p><p>　　The S7-300 is a modular PLC. It consists of Rack, CPU Module; Signal Module, Function Module, Interface Module, C

30、ommunications Processor, Power Module and Programming Module. The PLC system of the project contains three racks, the main rack communicated with Expansion rack by IM360/361. The Phase I of Sewage Treatment Phase has 23

31、analog input points, 3 analog output points, 222 digital input points and 68 digital output points. In this PLC hardware configuration, 15% of all reserve margins is s</p><p>　　Composition of PC Conitoring S

32、ystem</p><p>　　This paper takes the Chinese version WinCC 6.2 as systematic configuration software to realize the configuration function of superv ision appearance. It provides a variety of drivers for PLC,

33、which makes the connection of PLC and PC much easier and the variable list configured in STEP7 can be us ed directly when connected with WinCC. The functional block diagram for PC monitor system is shown in Figure 4.<

34、/p><p>　　“PC monitoring system” functional description: </p><p>　　1) Control function : to realize the real-time control of the on-line device in the main control room, such as equipments start/sto

35、p, analog output regulation, PLC operating parameters setting online, etc. </p><p>　　2) Display function : to show the running state of the device being controlled via the graphics and animation, and disp

36、lay the real-time operating parameters of the field device. </p><p>　　3) Archive management: to set up a production database and save the original data of the production for calculation and analys is, accord

37、ing to the change speed, the importance of operating parameters, the r eal-time and historical running state. </p><p>　　4) Alarm function: to realize different alarm grades according to different needs, when

38、 an analog value (such as current, pressure, water level, concentration, etc.) measured exceed the given range, or a digital value (such as motor start/stop, valves on/off) is out of order. </p><p>　　5) Prin

39、t function : to realize the real-time print of reports, graphics, various events and alarm. The print way can be divided into timed print, event trigger print and user-defined print. </p><p>　　6) Log managem

40、ent: to record the information for users to log in and out, in order to search the use interval for different users. </p><p>　　7) Rights management: to set corresponding visit protection for different users,

41、 and prevent the users unauthorized to visit the monitor system.</p><p>　　PLC Control Program</p><p>　　The system uses modular design to realize the program of PLC system via the STEP7 software.

42、 The program flow chart is shown in Figure 5.</p><p>　　The control system adopts modularization program, and falls into 10 subprogram according to the workshop in the whole techni cal procedures. In the main

43、 program, it can call each subprogram in proper order. First, writting an analog acquisition subprogram in the orgnization block 35, and the analog data will be refreshed every 100 millisecond. Then, the control program

44、which is classified as remote manual control and remote auto control can switch through the bit flags between the two ways. Remo</p><p>　　Conclusions</p><p>　　The automation system used in the s

45、ewage treatment is worthy of popularization, for it can meet the requirements of modern sewage treatment, reduce the day-to-day maintenance management, decrease the cost of sewage treatment, and ensure the operation and

46、water quality of effluent. With the development of engineering technology, the automation system in the sewage treatment plant will surely show its obvious advantages. The project was tested in 2010.10. The result turned

47、 out that the system is a</p><p>　　基于S7-300 PLC的污水處理自動(dòng)化系統(tǒng)的設(shè)計(jì)與應(yīng)用</p><p>　　摘要. 在縣級(jí)城市生活污水處理的需求，集散控制系統(tǒng)在城市污水處理自動(dòng)化系統(tǒng)的計(jì)劃提出的。其中的主要功能是通過(guò)組態(tài)軟件WinCC，西門子S7-300的城市污水處理的每個(gè)子系統(tǒng)的PLC監(jiān)控。該系統(tǒng)的功能主要有以下幾點(diǎn)，PLC的數(shù)據(jù)，協(xié)議轉(zhuǎn)換器，通

48、過(guò)光纖傳輸?shù)臄?shù)據(jù)的收集，項(xiàng)目，組態(tài)軟件實(shí)現(xiàn)實(shí)時(shí)數(shù)據(jù)存儲(chǔ)在數(shù)據(jù)庫(kù)和各種報(bào)告的發(fā)布形式，曲線顯示等報(bào)警事件。本文還提出了系統(tǒng)的系統(tǒng)名稱和詳細(xì)描述的想法。</p><p>　　關(guān)鍵詞 污水處理系統(tǒng) 集散控制系統(tǒng) 西門子S7-300 PLC WinCC組態(tài)軟件</p><p><b>　　1 引言</b></p><p>　　隨著中國(guó)經(jīng)

49、濟(jì)的快速發(fā)展，環(huán)保一個(gè)突出的問(wèn)題。污水處理是環(huán)境保護(hù)最重要的任務(wù)之一。隨著計(jì)算機(jī)技術(shù)和污水處理技術(shù)迅速發(fā)展，這是必要的監(jiān)控污水處理過(guò)程與先進(jìn)控制技術(shù)和設(shè)備。</p><p>　　內(nèi)蒙古呼和浩特市土默特左旗的污水處理項(xiàng)目是典型項(xiàng)目在呼和浩特市的縣級(jí)市，采用循環(huán)式活性污泥系統(tǒng)系統(tǒng)（CASS）處理廢水。于這個(gè)項(xiàng)目，我們?cè)O(shè)計(jì)的DCS系統(tǒng)，其控制系統(tǒng)采用西門子S7-300 PLC的監(jiān)控軟件是西門子WinCC6.2。<

50、/p><p><b>　　2 CASS工藝</b></p><p>　　CASS生化處理系統(tǒng)是一個(gè)復(fù)雜的系統(tǒng)多參數(shù)(如液位、水質(zhì)、流量、壓力等)、多任務(wù)(如水進(jìn)口,曝氣，沉淀，排水等），多設(shè)備（如潷水器，風(fēng)機(jī)，穩(wěn)壓器等）。它是整個(gè)生化處理系統(tǒng)的核心。CASS池主反應(yīng)區(qū)的工程，按照“曝氣，閑置，沉淀，和潷水器“的循環(huán)過(guò)程。其中，控制溶解氧在CASS池，厭氧段和好氧

51、段是核心。</p><p><b>　　3控制系統(tǒng)的結(jié)構(gòu)</b></p><p>　　自動(dòng)污水處理控制系統(tǒng)的結(jié)構(gòu)是集中管理和分散控制?？刂葡到y(tǒng)采用的控制方法結(jié)合遠(yuǎn)程自動(dòng)控制，遠(yuǎn)程手動(dòng)控制和領(lǐng)域的自動(dòng)控制。</p><p>　　為了確保污水處理系統(tǒng)運(yùn)行，主站和PLC從站是獨(dú)立的。如果一個(gè)子系統(tǒng)發(fā)生故障，也不會(huì)影響其他系統(tǒng)設(shè)備的正常運(yùn)行。即使整個(gè)控

52、制系統(tǒng)出現(xiàn)故障，它也可以及時(shí)調(diào)整自己到現(xiàn)場(chǎng)手動(dòng)控制模式，以確保污水處理系統(tǒng)的正常運(yùn)行。在中央控制室的電腦采用雙冗余模式，以實(shí)現(xiàn)實(shí)時(shí)監(jiān)控。兩臺(tái)服務(wù)器的待機(jī)彼此共同執(zhí)行監(jiān)測(cè)任務(wù)。如果一個(gè)服務(wù)器發(fā)生故障了，其他人可以承擔(dān)的任務(wù)，自動(dòng)保證系統(tǒng)能繼續(xù)提供服務(wù)無(wú)需人工干預(yù)的情況下。</p><p><b>　　4數(shù)據(jù)通信</b></p><p>　　S7系列PLC的通信網(wǎng)絡(luò)主要包

53、括以下內(nèi)容：多點(diǎn)陽(yáng)離子數(shù)據(jù)通信接口（MPI）協(xié)議的PROFIBUS，工業(yè)以太網(wǎng)，點(diǎn)至點(diǎn)連接，通過(guò)AS-I的通信過(guò)程。這個(gè)項(xiàng)目有PROFIBUS總線，工業(yè)以太網(wǎng)，點(diǎn)至點(diǎn)連接。</p><p>　　S7-300和WinCC之間的溝通</p><p>　　PLC和PC機(jī)通過(guò)工業(yè)以太網(wǎng)相互通信，PLC的傳輸通過(guò)光纖到PC機(jī)的配置軟件的實(shí)時(shí)數(shù)據(jù)庫(kù)的實(shí)時(shí)生產(chǎn)數(shù)據(jù)。PC可以監(jiān)視現(xiàn)場(chǎng)設(shè)備從很遠(yuǎn)的地方。因?yàn)?/p>

54、PLC在這個(gè)系統(tǒng)中選擇的是CPU315-2PN/DP，或已集成PROFINET接口。S7-300和WINCC之間的通信使用TCP / IP網(wǎng)絡(luò)協(xié)議。TCP/ IP網(wǎng)絡(luò)協(xié)議，是事實(shí)上的IT標(biāo)準(zhǔn)有關(guān)通信協(xié)議服務(wù)。雖然響應(yīng)時(shí)間是100毫秒左右的幅度，為應(yīng)用工廠控制，響應(yīng)時(shí)間是足夠的。</p><p>　　主站和從站PLC站之間的溝通</p><p>　　PLC主站采用西門子S7-300 

55、;PLC。 PLC 的ClO2車間使用西門子S7-200 PLC通信主站和從站PLC站之間采用PROFIBUS。PROFIBUS，國(guó)際化和開放的，不依賴于標(biāo)準(zhǔn)現(xiàn)場(chǎng)總線的設(shè)備制造商。這是一個(gè)用于控制工廠的現(xiàn)場(chǎng)總線自動(dòng)化車間級(jí)和數(shù)據(jù)通信，并控制現(xiàn)場(chǎng)設(shè)備級(jí)。PROFIBUS傳輸速度為9600波特?1.2×107波特，當(dāng)主系統(tǒng)啟動(dòng)時(shí)，一般線連接到的所有設(shè)備應(yīng)設(shè)置在相同的速度。這可以實(shí)現(xiàn)分散的數(shù)字控制和現(xiàn)場(chǎng)通信網(wǎng)絡(luò)現(xiàn)

56、場(chǎng)設(shè)備級(jí)，車間級(jí)到從而為工廠提供一個(gè)可行的解決方案實(shí)現(xiàn)全面的自動(dòng)化和智能化現(xiàn)場(chǎng)設(shè)備。處理器西門子S7-300 PLC模塊，CPU 315-2 PN / DP的，它有其自己的PROFIBUS接口。在S7-300 PLC Profibus網(wǎng)絡(luò)作為主站，S7-200 PLCProfibus網(wǎng)絡(luò)作為從站。 S7-200 PLC有沒(méi)有PROFIBUS通訊接口本身，因此它具有與主

57、站通過(guò)EM277的通信。</p><p>　　PLC之間的通信和電力設(shè)備</p><p>　　根據(jù)設(shè)計(jì)要求，PLC和權(quán)力之間的溝通需要建立的電流，電壓和功率，在電源設(shè)備應(yīng)監(jiān)測(cè)系統(tǒng)。西門子PLC的點(diǎn)至點(diǎn)的通信鏈路通過(guò)通訊模塊CP341的發(fā)電設(shè)備。電源設(shè)備提供了RS485半雙工異步串行通信接口通信，并采用MODBUS RTU通訊協(xié)議。</p><p>　　MODBUS協(xié)

58、議是在工業(yè)控制單元的網(wǎng)絡(luò)協(xié)議之一。由不同廠家生產(chǎn)的控制設(shè)備可以連接作為工業(yè)MODBUS協(xié)議，該設(shè)備在不同網(wǎng)絡(luò)中的網(wǎng)絡(luò)鏈接可以進(jìn)行數(shù)據(jù)通信。MODBUS網(wǎng)絡(luò)可以連接多個(gè)上一條線，每個(gè)設(shè)備的設(shè)備可以設(shè)置通訊地址本身。每個(gè)控制器可以區(qū)分設(shè)備的地址。此外，它發(fā)送什么消息由地址決定。如果需要回應(yīng)，控制器將建立信息反饋和發(fā)送MODBUS協(xié)議。在另一個(gè)網(wǎng)絡(luò)，有轉(zhuǎn)換的MODBUS消息幀和封裝結(jié)構(gòu)協(xié)議。轉(zhuǎn)換也擴(kuò)展的方式來(lái)解決問(wèn)題，如地址，路由路徑及錯(cuò)誤檢

59、測(cè)在特定的網(wǎng)絡(luò)。</p><p>　　5西門子S7-300硬件</p><p>　　S7-300是一個(gè)模塊化的PLC。它由機(jī)架，CPU模塊，信號(hào)模塊，功能模塊，接口模塊，電源模塊和編程模塊，通信處理器。該項(xiàng)目的PLC系統(tǒng)包含三個(gè)機(jī)架，主要機(jī)架與擴(kuò)展機(jī)架IM360/361傳達(dá)。第一階段的污水治療階段有23個(gè)模擬輸入點(diǎn)，3個(gè)模擬量輸出點(diǎn)，222個(gè)數(shù)字輸入分和68個(gè)數(shù)字輸出點(diǎn)。在此PLC的硬件配

60、置，15％的所有儲(chǔ)備的利潤(rùn)率是預(yù)留的，這是第二階段的闊葉。 S7-300 PLC系統(tǒng)硬件框圖如圖3所示。</p><p>　　6 PC Conitoring系統(tǒng)組成</p><p>　　以中國(guó)版本的WinCC6.2系統(tǒng)配置軟件實(shí)現(xiàn)，監(jiān)督外觀配置功能。它提供了多種司機(jī)為PLC，使PLC與PC的連接更容易和在STEP7中配置的變量列表可以是我們教育署直接與WinC

61、C連接時(shí)。電腦監(jiān)控系統(tǒng)的功能框圖如圖4所示。</p><p>　　“電腦監(jiān)控系統(tǒng)”的功能描述：</p><p>　　1）控制功能：主要實(shí)現(xiàn)實(shí)時(shí)控制的上線的設(shè)備控制室設(shè)備，如啟動(dòng)/停止，模擬輸出調(diào)節(jié)，PLC運(yùn)行在線等參數(shù)設(shè)置。</p><p>　　2）顯示功能：顯示設(shè)備的運(yùn)行狀態(tài)，通過(guò)控制圖形和動(dòng)畫，顯示該領(lǐng)域的實(shí)時(shí)運(yùn)行參數(shù)設(shè)備。</p><p&g

62、t;　　3）檔案管理：建立一個(gè)生產(chǎn)數(shù)據(jù)庫(kù)，并保存原始數(shù)據(jù)計(jì)算和分析產(chǎn)品的生產(chǎn)，根據(jù)變化的速度，運(yùn)行參數(shù)的重要性，在R的EAL時(shí)間和歷史的運(yùn)行狀態(tài)。</p><p>　　4）報(bào)警功能：實(shí)現(xiàn)不同的報(bào)警級(jí)別，根據(jù)不同的需求，當(dāng)模擬值（如電流，壓力，水位，濃度等）測(cè)量超過(guò)給定的范圍內(nèi)，或數(shù)字值（如電機(jī)啟動(dòng)/停止，閥門開/關(guān)）的訂單。</p><p>　　5）打印功能：可實(shí)現(xiàn)實(shí)時(shí)打印報(bào)告，圖形，各種

63、活動(dòng)并報(bào)警。定時(shí)打印，事件觸發(fā)打印和打印方式，可分為用戶定義的打印。</p><p>　　6）日志管理：記錄的信息，以便為用戶登錄和注銷搜索針對(duì)不同用戶的使用間隔。</p><p>　　7）權(quán)限管理：為不同的用戶設(shè)置相應(yīng)的訪問(wèn)保護(hù)，防止未經(jīng)授權(quán)的用戶訪問(wèn)的監(jiān)控系統(tǒng)。</p><p>　　7  PLC的控制程序</p><p>　　

64、該系統(tǒng)采用模塊化設(shè)計(jì)，實(shí)現(xiàn)PLC控制系統(tǒng)的方案，通過(guò)在STEP7軟件。程序流程圖如圖5所示。</p><p>　　控制系統(tǒng)采用模塊化的程序，分成10子程序根據(jù)技術(shù)性CAL在整個(gè)程序的研討會(huì)。在主程序中，可以在正確的順序調(diào)用每個(gè)子程序。首先，寫一個(gè)模擬采集在組織塊35，子程序和模擬數(shù)據(jù)將被刷新每100毫秒。然后，控制計(jì)劃被列為遠(yuǎn)程手動(dòng)控制和遠(yuǎn)程自動(dòng)控制，可以通過(guò)兩種方式之間的切換標(biāo)志位。遠(yuǎn)程手動(dòng)控制，可以人為控制的

65、設(shè)備的啟動(dòng)/停止，遠(yuǎn)程自動(dòng)控制可自動(dòng)調(diào)節(jié)設(shè)備的狀態(tài)，通過(guò)對(duì)現(xiàn)場(chǎng)的變化參數(shù)。所以程序可以自動(dòng)執(zhí)行，并及時(shí)為每個(gè)周期，所有的設(shè)備可以自動(dòng)停下來(lái)控制時(shí)有連鎖故障。 MODBUS使用通信電源米多點(diǎn)輪詢模式。</p><p><b>　　8結(jié)論</b></p><p>　　在污水處理中使用的自動(dòng)化系統(tǒng)是值得推廣的，因?yàn)樗軡M足現(xiàn)代污水處理的要求，減少日常的一天維護(hù)管理

66、，降低污水處理成本，并確保運(yùn)行和出水的水質(zhì)。隨著工程的發(fā)展技術(shù)，在污水處理廠的自動(dòng)化系統(tǒng)必將顯示其明顯的優(yōu)勢(shì)。該項(xiàng)目進(jìn)行了測(cè)試于2010.10。結(jié)果竟然系統(tǒng)是一個(gè)先進(jìn)，可靠，操作簡(jiǎn)單的控制系統(tǒng)，從而能夠更好地解決一些問(wèn)題，如自動(dòng)化低，可靠性低，大量的時(shí)間延遲和其他一些在過(guò)去的污水處理存在問(wèn)題。</p><p>　　浙江工業(yè)大學(xué)教科學(xué)院</p><p>　　畢業(yè)設(shè)計(jì)外文資料翻譯</p&

67、gt;<p>　　設(shè)計(jì)題目： 龍門刨床刨臺(tái)運(yùn)動(dòng)模擬器的設(shè)計(jì) </p><p>　　學(xué)生姓名： 　 </p><p>　　學(xué) 號(hào)： </p><p>　　專 業(yè)：

68、 </p><p>　　外文出處：Communications in Computer and Information Science, 1, </p><p>　　Volume 216, Advances in Computer Science, Environment, Ecoinformatics, and Education, P

69、ages 552-556 </p><p>　　指導(dǎo)教師： </p><p>　　2012年 2 月 12 日</p><p>　　Research on Virtual Experiment System on PLC</p><p>

70、;　　Education Based on Teaching Materials</p><p>　　Abstract. This paper presents virtual models of virtual experiment system, which are employed in the process of education of programmable logic control-ler (

71、PLC) programming. Within control laboratory, the virtual models appear as well-suited alternate to physical-mechanical or process control model, whose feasibility, in laboratory conditions, is sometimes complicated. As w

72、e do both, the development and employment of virtual models, the paper includes ap-proach to virtual models development, de</p><p>　　Keywords: Programmable logic controller (PLC), supervisory control and da

73、ta acquisition (SCADA), Virtual Model, Mathematical Model.</p><p>　　Introduction</p><p>　　Modern automated systems typically use programmable logic controllers to orchestrate and coordinate the

74、plants being automated. Clearly there is a great need for engineers with strong skills and knowledge in this area. But there are many challenges in teaching PLC programming to students.</p><p>　　Although the

75、 PLC is often covered in undergraduate automation courses, many educational institutions lack resources to help students to become proficient PLC users [1]. Disadvantages of traditional labs include the need for a qualif

76、ied teacher, the demand on institutional space, time constraints on the students and on the safety problems, recurring maintenance, etc. Experimental laboratories, however, represent a significant investment of both fund

77、s and space, which schools may not be able to me</p><p>　　PLC simulation software can be divided into two categories which are Virtual PLC and Virtual Environment. Virtual PLC is the emulation package for PL

78、C programming software. Virtual PLC, used with corresponding controller, lets users run and debug the application code while at computer. The leading engineering companies usually provide the Virtual PLC. CX-Simulator is

79、 a tool that functions as a virtual Omron PLC. S7-PLCSIM allows users to simulate the operation of a Siemens S7 PLC and users can t</p><p>　　Virtual Environment is a functional ladder logic design and PLC si

80、mulation software program that incorporates the basic functions used in PLC ladder programming. Virtual Environment functions include inputs, outputs, timers, counters and registers. Some Virtual Environments perform t

81、he simulation of the control program, and the plant model visualizer shows the corresponding plant model reflecting the changing states of the virtual system during the PLC simulation. It becomes much easier for us</p

82、><p>　　Virtual PLC and Virtual Environment have weakness of connectivity to real PLC system. Connectivity to plant devices is key to PLC education. The virtual experiment system must maximize students’ choices

83、with the broadest possible communication options for industrial automation and information devices. SCADA software provides the largest selection of connectivity options to hundreds of PLCs and other hardware devices. SC

84、ADA software makes device integration for seamless connectivity to any PLC. T</p><p>　　Overview of the Virtual Experiment System</p><p>　　In this paper, a virtual experiment system is implemente

85、d with a real PLC and SCADA software. A standard PLC is used to control of the virtual models in this sys-tem. The SCADA is integrated with the system to simulate the plant. The equipment used in experimental setup is sh

86、own in Fig. 1. </p><p>　　The parts of the experimental setup are: Serial cable for communication between SCADA (PC) and PLC, PLC for control of the system, SCADA screen based on Kingview, and PC.</p>

87、<p>　　PLC must be connected to PC by special serial cable. Kingview is a kind of SCADA software with abundant functions. Kingview provides integrated development environment. Some 2D models of plant are developed

88、on Kingview. The main function of Kingview is a communication module supporting communication between virtual model and a real PLC. Kingview supports a wide range of PLC communication features and allow users to select i

89、n a wide range of PLC brands. Virtual models are the core of virtual exp</p><p>　　The Architecture of Virtual Model</p><p>　　The architecture of the virtual model consists of two layers, a graph

90、ic model layer and a mathematical model layer. The graphic model layer shows the corresponding plant models (2D or 3D graphic models) reflecting the changing states of the virtual system during the simulation. It becomes

91、 much easier for users to verify the PLC program through the plant model animation. 2D models represent some simple graphical models of process control systems. The 2D models are built by Kingview graphical desi</p>

92、;<p>　　The mathematical model layer is the core of simulation. Mathematical modeling is the process of creating a mathematical representation of a plant. During building a mathematical model, we will decide what f

93、actors are relevant to the plant and what factors can be de-emphasized. The mathematical models contain output and input variables and obtain the mathematical relationship between the input and output tags. All the plant

94、 models are discrete-time models and sampling frequency is given. Fig 3 sh</p><p>　　Illustrations</p><p>　　According to [5], we build a chemical reactor model called "stirring tank" is

95、 depicted below. The top inlet delivers liquid to be mixed in the tank. The tank liquid must be maintained at a constant temperature by varying the amount of steam supplied to the heat exchanger (bottom pipe) via its con

96、trol valve. Variations in the temperature of the inlet flow are the main source of disturbances in this process. We design the animation of reactor by Kingview graphical designer in Fig 4.</p><p>　　Heat exc

97、hange model transfer function mode ls how a change in the voltage to drive the steam valve opening affects the tank temperature, while the transfer function is</p><p>　　Disturbance model transfer function mo

98、dels how a change in the voltage to drive the liquid flow valve opening affects the tank temperature, while the transfer function is </p><p>　　To discretize these transfer functions using zero-order hold on

99、 the inputs and a sample time of 5 seconds, and we get the discrete-time models. Heat exchange model discrete-time model is</p><p>　　Disturbance model discrete-time model is </p><p>　　The relat

100、ionships among the tank temperature, the voltage of steam valve and the voltage of liquid flow valve are </p><p>　　We create y, yp, xp, yd, xd tags in Kingview. According to Eq. 3~5, Kingview calcu-lates th

101、em every 5 seconds and upgrade the graphical status. The initial values of these tags are zero. To regulate the tank temperature y around a given setpoint, students can use a real PLC to control the virtual valve opening