PLC未来发展趋势外文翻译

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1、学校代码：11517 学 号：201050712108 HENAN INSTITUTE OF ENGINEERING 文献翻译 题 目 基于P LC的自动售货机控制 系统设计 学生姓名 专业班级 电气工程及其自动化0921班 学 号 20095071 系 （部） 电气信息工程系 指导教师(职称) 完成时间 2011年 3 月 2日 摘自可编程控制器在过程自动化中的应用Ahti Mikkor,Lembit RoosimolderDepartment of Product Development,Institute of Machinery,Tallinn technical University

2、,Ehitajate tee 5,19086Tallinn.摘要：目前，控制问题解决了各种各样的技术操作部分：电子，液压，气动和机械。函数- nality，可靠性和控制系统的价格是阻止开发的理由。本文集中于可编程逻辑控制器（PLC），以五年在这方面的发展经验为基础。成功的解决方案是问题重点。具体的硬件，控制器编程的问题、数据/信号的交换和人机界面进行审议。实际的建议，需要根据具体的方法来开发可编程控制器。对于可能出现的错误和警告，提出可以帮助避免方法。关键词：可编程控制器、自动化、自动化系统、过程自动化1引言现代的机器包括电子和机械两部分。平衡两方面因素，初步规划和方案选择对最终结果起着至关重

3、要的作用。在控制方法的选择，继电器，专用设备，可编程逻辑控制器（PLC）和电子制造技术的发展。这篇文章是基于PLC集中- S的经验，拥有超过5年的PLC - S的实际工作经验中收集的。双方强弱，积极和消极的做法进行了讨论。建议使用可编程控制器帮助解决。在规划基于PLC系统中最重要的决定是选择处理器类型。误区是意味着修改额外费用或扩展完全新设备的需要。最常见的错误是高估小型处理器编程的可能性。有选择PLC的几种方法。不幸的是，他们大多集中在电气方面的PLC - S和允许的最大计数信号。他们不涉及分析，以确定用户程序或通信可能的特殊需要。基于几个现有的方法，实践经验和未来趋势的选择为开PLC的开发

4、提供新的方法。阿赫蒂瓦尔Mikkor已获得通过采取在超过15个大范围的自动化项目的一部分，以他的经验，这些项目包括电力消耗在AS昆达北欧水泥工厂监控系统的开发，更新测试流量计钻机，建设城镇Rakvere和普亚，污水处理厂在城里Jogeva和发展动力涡轮安全系统，污水处理厂在塔尔图监测网络系统的集中供热。2可编程控制器在投票站的使用2.1正面论据主要优势是灵活性提供可编程控制器（杰克，2003年）该系统的行为可以很容易地通过计划，没有任何其他的改动。例如特殊装置使控制算法很难实现任何改变。灵活性使得PLC的- S经常更换适合应用在机器人的例子。在PLC - S的投入和产出之间的关系是由用户程序决

5、定。通过使用先进的编程技术比任何硬连接解决方案容易得多，以实现复杂的控制算法。它使PLC在复杂的任务很有竞争力。例如，在控制化学过程，特别模块，让大量不同的信号被连接到PLC系统。PLC - S的使用，应考虑应用，需要一些“特殊”的输入或输出信号。典型的例子是利用定位高速输入参考的数据。通常个人电脑的可视化软件是由可编程序控制器PLC- S控制，也有一些特殊设备的PC软件包。宽的PLC - S的通信选择范围使得它能够收集到一个中央控制点。搜集现场的所有设备的信息。窄的PLC - S的通讯线路允许使用从本地过程控制系统的其他部分中收集信息。现代通讯技术实现远程诊断和配置（杰克，2003年）。这两

6、方面显着降低了系统的总体维护成本。2.2没有配备足够的内存来存储数据虽然未来的趋势在PLC内存大小，（录像机）专用设备的增长仍然是更适合于独立的数据记录应用。对于网络解决方案，有可能使用可视化软件包一起与PLC - s到存档于任何数据库格式收集必要的数据。如果记录的数据量小或者有控制功能也包括在内，采用PLC - S是合理的。关于它的可视化软件，知道他们在标准版本的大多数不支持脱机录音通讯故障后，使我们无法获得向后从PLC的数据。对PLC的现代通讯选项包括，例如以太网标准协议。人们很容易用数据自动化系统的通信运营商中获得。时间已经证明，最好的做法是保持这两方面分离的，如果有一个经常上网的通信需

7、求。几乎没有时间可追溯网络超载问题，也可能在自动化系统的通信。所有的PLC - S的需要进行编程，所有的编程作品包括在控制算法和意外错误的风险。特种设备是行之有效的，并且通常解决这类问题的。如果有的话，它是经济的使用特殊设备。安全应用需要最高的可靠性程度，应该包含最简单的设备和电路。有一个规则，每一个链的新环节可能降低整体的可靠性。在小型系统应用中，经常节省成本使用中继电路，而不是使用PLC的- S的。3今后的趋势过程自动化系统的进展是针对所谓的完全自动化，所有的人所要做的就是进入该产品的参数和其他一切工作由机器（松香，2000年）协调。虽然目标遥遥领先，表明在这个方向的趋势运动。首先，系统变

8、得越来越规范。从大型制造商组织到家庭的产品。其目的是减少对来自同一公司不同的设备配置和维护工作所需的知识量。同样重要的是这种方式构建的应用程序很容易扩展。其次，沟通的重要性正在上升（休斯，2000）。有很多原因，更多的要领有：更好的系统是不同部分的合作。 降低成本的布线。减布线结果增加了故障率，也增加了那些发生的严重程度。 传感器与驱动器可以在从传统方法相比，如果使用的处理器覆盖更长的距离。 提高了系统的可扩展性。在增加新设备时以最低的成本。 在某些情况下，最好是让许多小型的独立模块和网络架构。该解决方案使系统继续工作，尽管一些地区已经失败。 方便的通信网络故障诊断为远程管理提供了可能性。中央

9、操作站，可形成相对容易。 可将设备连接形式（OPC基金会，2003）不同的生产厂家。第三个重要趋势是散布所谓的软件控制器或软PLC - S的（西门子股份公司，2003年）的使用。这些都是电脑软件为基础的解决方案，通过通信网络与现场设备。有没有需要的处理器模块，使用的PC资源。有些软PLC - S仍然为PC处理器卡（图1）。可靠的通信网络是必不可少的。软PLC - S是非常适合于个人电脑的数据存储数据采集应用的。图1。西门子的SIMATIC WinAC插槽式PLC 412第四，组合装置（图2）同时包含操作员面板和中等规模的处理器模块得到普及（西门子股份公司，2002）。这个解决方案的可能性很低，

10、一些组件的重用使整个包便宜。西门子SIMATIC组合设备的C7 613第五，处理器软件接管从PC软件性质。收集的数据可以很容易地从生产到Office应用程序转移（西门子股份公司，2000）。4 可编程控制器的控制方法可编程控制器的控制方法的选择是形成一个应用程序所需的特定属性列表中选择可编程控制器方法的开发。有九个准则，其结果如表1所示。通过比较做出选择与控制器的技术数据结果表。以下是每一个参与标准的简短描述。溶液的性质决定的是旧系统或全新的发展扩大。在第一种情况下的系统和硬件的要求是有限的架构已经存在解决方案。使用来自同一公司的硬件，使维修更方便，避免了整合的问题，将产品形式出现时，使用不同

11、的生产厂家。例如，许多硬件制造商结合自己的具体通信接口，直接将处理器模块和通用协议组合。每一个需要特殊模块的（西门子股份公司，2003），它也可以减少备件库存金额，在系统全部采用同一类型的硬件。最大的电力输入，允许输出的数量用标准来确定处理器。如果复杂的控制算法和非标准功能是必需的，它不是最重要的参数了。一般来说是金钱储蓄用于输入输出信号之一是更大的处理器模块，它来自于几个较小的邻近的位置。在这种情况下，不会对通信网络的需要，也将会更容易编程。特殊信号和模块通常为中型和大型控制器只提供家庭使用。许多微控制器甚至没有可能性，加上模拟输出（西门子股份公司，2003）。在某些情况下是使用特殊的模块的

12、唯一途径，其他的（定位）这只是一个机会，为了省钱。传感器和执行器的布局可有很大差异，有时远离传感器执行器（中长管抽吸液体）数公里。在这种情况下，特殊的通讯网络（现场总线，如- inteface）可能是唯一的解决办法。如果不是，它至少可以节省成本，减少布线工程。并非所有可编程控制器通信协议的接口，处理器的性能在复杂的应用中有非常重要的作用。最常见的问题是内存不足的时，有时也有数据存储器。内存要求可估计的输入和输出信号的数量。但在实践中100个数字输入输出点系统通常有3倍以上10个数字输入输出点的系统较小的程序。只有这样，才能准确地估计项目的规模。计划特色包括特殊程序功能的需要。不同的应用领域有一

13、些通常使用的功能，例如，在楼宇自动化温度控制中，编程要简单得多，如果这些功能已经进入系统软件中内置的处理器。在过程自动化2个数字输出（上下）闭环PID调节是很常用的。这可能是一个惊喜，但它不符合大多数微控制器（西门子股份公司，2003），对于一般的程序员它太复杂，开创了自己的调节器的标准功能包括在内。基本上有2个解决方案：以避免这方面的建设和使用适用的控制器。成果表现：交流在当今的自动化系统应用越来越广泛。在某些情况下，作为条形码阅读器或电子权值非标准化装置必须到系统中。然后，它的协议有至关重要的编程（自由港编程）功能。标准化协议的具体模块需求：工作条件，通常可以克服使用特殊柜，但也有，改善了

14、电磁干扰，湿度和振动性特定的系列可编程控制器。在非常脏的环境中所有的冷却风扇都必须配备过滤器。5结论可编程控制器的主要好处是：灵活实现方便的沟通和复杂的控制算法替代方案时应考虑可靠性系统尽量简单可记录特殊设备 适当的解决方案和硬件的选择对最终结果有很大的影响。如果这一步失误，一些项目的总体预算方案可能要发生变化，一些硬件要更换。根据他的实际经验，笔者已经形成了一个选择可编程控制器的方法。它有9个标准的：-输出允许（数字，模拟，输入，输出）的解决方案（新的或现有）的电气输入：最大数量自然需要特殊的模块（高速数字输出）传感器与致动器布局（本地或周边）处理器（程序和数据存储器）特色方案（特殊功能）通

15、讯需求（现场总线，ASCII）的性能工作条件（湿度，温度，振动，粉尘）没有什么方法保证总是指出最好的解决方案，但使用确定的方法能避免了失误。参考文献1 Hughes, T. A. Programmable Controllers, Third Edition. ISA The Instrumentation, Systems, and Automation Society, 2000, 334 p. 2 Jack, H. Automating Manufacturing Systems with PLC-s, 828 p., Available: 3 http:/claymore.engine

16、er.gvsu.edu/jackh/books/plcs/pdf/plcbook4_2.pdf,Accessed:3.10.2003 4 LOGO! Manual. Siemens AG, 2003, 312 p. 5 OPC Foundation homepage: http:/www.opcfoundation.org/, Accessed: 9.11.2003 6 Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. Master Thesis in Estonian. 7 Berger, H.

17、 Automating with SIMATIC. Siemens AG, 2003, 214 p. 8 SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p. 9 SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p. 10 SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG 2000, 468 p. 4th Interna

18、tional 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 RoosimlderDepartment of Product Development, Institute of Machinery, Tallinn Technical University, Ehi

19、tajate 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 qu

20、ality 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

21、 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

22、, 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

23、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

24、 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 de

25、vices. 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 to determine possible special

26、 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

27、 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 Plva, waste water treatment plant in town Jgeva and development of monitoring system for central

28、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

29、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

30、 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 co

31、nsidered 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 software packages. Wide range of communica

32、tion 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 diagn

33、ostics 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 (re

34、corders) 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 amounts are small or there are also control fun

35、ctions 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 backwards from PLC. Modern communication options

36、 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 tra

37、ceable 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, its ec

38、onomically 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 its often cost saving to use relay-bas

39、ed 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 (Rosin, 2000). Although the destination lies f

40、ar 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. Its also

41、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 p

42、robability, 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 some cases it is better to make architecture

43、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 connec

44、t 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

45、 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-s. Figure 1. Siemens Simatic WinAC Slot PL

46、C 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 2. Combo device Siemens Simatic C7-613 Fif

47、thly, 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 specific list of required properties for selectin

48、g 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 solution determines weather it is expanding

49、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 when using products form different manufa

50、cturers. 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 amounts when using same type hardware all o

51、ver 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 saving to use one bigger processor module

52、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 controller families only. Many microcontrol

53、lers 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, sometimes the sensors are located several kil

54、ometres 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 interfaces for communication protocols. P

55、roperties 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-output points system often has 3 times smal

56、ler 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 functions, for example temperature control in bu

57、ilding 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 included in most of the microcontrollers (Siemens

58、 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 Communication is becoming more important in nowad

59、ays 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 existence of specific modules. Working conditio

60、ns 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 have to be equipped withfilters.5. CONCLUSI

61、ONS 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 is necessary Initial selection of appropr

62、iate 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 formed a method for selecting programmable con

63、troller. 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 periphery) properties of processor (program and data memory) program specialities (special functions) communication needs (Profibus, ASCII) working conditions (humidity, tempe