plc英文资料和中文翻译.doc

1 PLC英文资料1.1 MotivationProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in 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 (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days Moody and Morley, 1999.Although PC based control has started to come into place, 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 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 of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating Moody and Morley, 1999, p. 110:If houses were built like software projects, a single woodpecker could destroy civilization.”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 dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other 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 PLC-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 of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs Rockwell, 1999.In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.1.2 Objective and Significance of the ThesisThe objective of this thesis is to develop 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 discrete 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 managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of the automation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.2 PLC英文资料A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications 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 to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspects.Customer-Driven ManufacturingIn modern manufacturing, systems are 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 economically 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 industrial practice.Higher Degree of Design Automation and Software QualityStudies have shown that programming methodologies in automation systems have not been able to match rapid 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 major 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 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999 have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancing the knowledge of efficient program and system design.A systematic approach 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 reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.System ComplexityThe 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. 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 redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs Simmons et al., 1998.3 PLC英文资料Design Theory DevelopmentToday, the primary focus of most design research is based on mechanical or 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 design 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. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.Application in Logical Hardware DesignFrom a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex 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 functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.PLCPLC（programmable logical controller）face ever more complex challenge these days. Where once they quietly relays and gave an occasional report to a corporate mainframe, they are now grounded into cells, give new jobs and new languages, and are forced to compete against a growing array of control products. For this years annual PLC technology update, we queried PLC makers on these topics and more.Programming languagesHigher level PLC programming languages have been around for some time, but lately their popularity has been mushrooming. As Raymond Lavelle, vice president and general manager, Siemens Energy and Automation. Inc, Programmable Controls Division, points out :”As programmable controls are being used for more and more sophisticated operations, languages other than ladder logic become more practical, efficient, and powerful. For example, its very difficult to write a trigonometric function using ladder logic. ”Languages gaining acceptance include Boolean, control system flowcharting, and such function chart languages as Graphtec and its variations. And theses increasing interest in languages like C and BASIC.PLCs in process controlThus far, PLCs have not been used extensively for continuous process control. Will this continue? ”The feeling that Ive gotten,” says Ken Jeannette, manager, product planning, Series One and Series Six products, at GE Frame North America, is that PLCs will be used in the process industry but not necessarily for process control.”Several vendors-obviously betting that the opposite will happen-have introduced PLCs optimized for process applications. Rich Ryan ,manager, commercial marketing, Allen-Bradley Programmable Controls Div, cites PLCs increasing use in such industries as food, chemicals, and petroleum. Ryan feel there are two types of applications in which theyre appropriate.”One, he says, is where the size of the process control system thats being automated doesnt justify DCSdistributed control systems.With the starting price tags of those products being relatively high, a programmable controller makes sense for small, low loop count applications. The seconds where you have to integrate the loop closely with the sequential logic. Batch controller sere prime examples, where the sequence and maintaining the process variable are intertwined so closely that the benefits of having a programmable controller to do the sequential logic outweighs some of the disadvantages of not having a distributed control system.”Bill Barkovtz, president of Triconex, predicts that all future controllers that come out in the process control system business will embrace a lot more PLC technology and a lot more PLC functionality than they ever did before.”Communications and MAPCommunications are vital to an individual automation cell and to the automated factory as a whole. Weve heard a lot about MAP in the last few years, and a lot of companies have jumped on the band wagon. Many, however were disappointed when a fully-defined and completed MAP specification didnt appear immediately. Says Larry Kumara:”Right now , MAP is still a moving target for the manufacturers specification that is not final. Presently, for example, people are introducing products to meet the MAP 2.1standard.Yet 2.1-based products will be obsolete when the new standard for MAP,3.0is introduced.”Because of this, many PLC vendors are holding off on full MAP implementations. Omron, for example , has an ongoing MAP-compatibility program, but Frank Newborn, vice president of Omrons Industrial Division, reports that because of the lack of a firm definition, Omrons PLCs dont yet talk to MAP.Since its unlikely that an individual PLC would talk to broadband MAP anyway, makers are concentrating n proprietary networks. According to Sal Provanzano, users fear that if they do get on board and vendors withdraw from MAP, they ll pulse width modulation control system be the ones left holding a communications structure thats not supported.PLC IntroductionProgrammable controller is the first in the late 1960s in the United States, then called Plc programmable logic controller (Programmable Logic Controller) is used to replace relays. For the implementation of the logical judgment, timing, sequence number, and other control functions. The concept is presented Plc General Motors Corporation. Plc and the basic design is the computer functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, such as the advantages of cheap prices combined controller hardware is standard and overall. According to the practical application of target software in order to control the content of the user procedures memory controller, the controller and connecting the accused convenient target.In the mid-1970s, the Plc has been widely used as a central processing unit microprocessor, import export module and the external circuits are used, large-scale integrated circuits even when the Plc is no longer the only logical (IC) judgment functions also have data processing, PID conditioning and data communications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition : programmable controller is a digital electronic computers operating system, specifically for applications in the industrial design environment. It used programmable memory, used to implement logic in their internal storage operations, sequence control, timing, counting and arithmetic operations, such as operating instructions, and through digital and analog input and output, the control of various types of machinery or production processes. Programmable controller and related peripherals, and industrial control systems easily linked to form a whole, to expand its functional design. Programmable controller for the user, is a non-contact equipment, the procedures can be changed to change production processes. The programmable controller has become a powerful tool for factory automation, widely popular replication. Programmable controller is user-oriented industries dedicated control computer, with many distinctive features.First, high reliability, anti-interference capability;Second，programming visual, simple;Third, adaptability good;Fourth functional improvements, strong functional interface.译文1.1动力1968年，Richard E. Morley创造出了新一代工业控制装置可编程逻辑控制器(PLC),现在，PLC已经被广泛应用于工业领域，包括机械制造也、运输系统、化学过程设备、等许多其他领域。初期可编程控制器只是用一种类似于语言的软件逻辑于代替继电器硬件逻辑，并且使开发时间由6个月缩短到6天。虽然计算机控制技术已经产生，但是PLC控制因为它的高性能、成本低、并且对恶劣的环境有很强的适应能力而在工业控制的广泛应用中保持优势。而且，尽管硬件的价格在逐渐下跌，据估计，根据Frost和Sullivan对PLC市场的调查研究表明，每年销售硬件的价格要比销售PLC的价格（一千五百万）至少多出八十亿美元。PLC的创造者Richard E. Morley十分肯定的认为目前PLC市场是一个价值五十亿的工业虽然PLC广泛应用于工业控制中，PLC控制系统的程序依然和语法有关。和软件过程一样，PLC的软件设计也以同样的方式会遇到软件错误或危机。Morley在演讲中着重强调了这个方面。如果房子建造的像软件过程一样，那么仅仅一只啄木鸟就可以摧毁文明。特别的，PLC程序要解决的实际问题是消除软件错误和减少老式梯形逻辑语言的花费。尽管PLC的硬件成本在继续下降，但是在工业控制上减少梯形逻辑的扫描时间仍然是一个问题，以至于可以用到低耗时的PLC。一般来说，和其他领域相比生产PLC的周期要短很多。例如，在实践中，VISI设计是一种有效的计算机辅助设计。PLC不需要使用目前的以软件设计为基础软件工程方法论，因为PLC程序要求对软件和硬件搜都要考虑到。因此，软件设计越来越成为花费动力。在许多的工业设计工程中，超过 的人力分配给了控制系统设计和安装，并且他们要对。PLC程序测试和排除错误，再者，PLC控制系统不适合设计对适应性和重构有越来越多要求的生产系统。一个更深入的问题是在大规模的工程中软件越来越复杂，促使要有一个系统化的设计方法论。1.2主题的客观性和重要性。主题的客观性是为PLC自动控制系统建立一个系统化的软件设计方法论。这个设计方法论包括以状态转换模型为基础的精确的描述，这个转台转换模型是自动控制系统的抽象系统。方法论还包括一个逐步的设计过程，并且要设置一个设计规则，这样才能为一个成功的设计提供导向和方法。这项研究的真正目的是找到一个减少控制软件发展过程的不稳定性的方法，也就是说，减少程序和调试时间以及他们的变化，以增强自动控制系统的适应性，并且通过调整软件使得软件可以再度使用。这样的目的是为了克服目前程序策略的不足之处，而目前的程序策略是以个人软件开发者的经验为基础的。2译文一个系统化的设计PLC程序的方法可以克服传统程序生产控制系统的缺点，并且在一些工业应用总有很大的不同。自动控制系统是状态模型用公式语言或等价的语言描述的。公式描述对被控制的系统的行为提供一个精确的描述。可以通过分析估计看状态模型是否达到想要的目标，第二，状态模型的描述提供结构描述，这个结构描述可以说明逻辑要求和如细节安全规则的限制。第三，好的控制系统设计是对自动控制代码生成有益的一种能够产生可执行的控制软件的能力，不同的逻辑控制器可以减少程序扫描时间和执行那个时间。特别的，这个主题与随后的部分的是有关的。订制生产在现代制造业中，系统是用过程和结果的革新来描述的，变得Customer-Driven，并且因此不得不改变系统性能以快速做出反应。因此，一个大的挑战是提供技术以限制自动控制系统对变化需要和新机会的反应，所以，设计和操作知识可以实时的被再次利用，在工业实践中提供了一个重要的竞争面。高水平的自动化设计和软件质量研究表明，在自动化系统中，程序实现的方法已经与计算机资源应用的急速增长不能匹配。例如，可编程逻辑控制器（）程序仍然依靠一种方便的有逻辑梯形图的程序实现模式。结果，程序上的延迟和资源成了生产工业过程的主要绊脚石。在可编程逻辑控制器程序设计过程中，测试和调试可能会占用超过百分之五十的人力。在发展和传播“”已经形成标准IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999，但是，基本上这些标准都不能参与有效的程序和系统设计方面知识的革新。系统的方法通过使用原有的软件模块，有助于增加设计自动化的水平，同时也将提供一种可管理的大规模系统设计的方法。同样的，它也将改善软件的质量的可靠性，以及关系到系统的较高安全标准，尤其是这些对环境有危害影响的，比如：机场控制、公共铁路运输。系统复杂性：软件工业被认为是系统性能的破坏者和系统复杂性的产生者。逐渐下降的硬件价格，破坏了对通过优化程序获得的软件性能的需要。其结果是，一方面造成了大量而低效率的程序代码，另一方面并没有获得高的硬件性能。其次，软件变得难以掌握其程度的复杂；在现代自动化系统中，软件设计和保持系统本质几乎变得不可能。尤其是，可编程逻辑控制器（）程序设计从二十五年前的两条主线，发展到现在的成千上万条。现在安全性增加了，例如，关于防火的新措施，以及现代自动化系统的柔韧性增加了程序设计过程的复杂性。因此，软件的使用周期花费是总共花费的一个固定不变的增长部分。百分之八十到九十的花费用于软件维护、调试、优化（改进）、和扩展以满足不断变换的需求。3译文3设计理论发展目前，大部分设计研究的主要焦点都集中在机械和电子产品上。这种有目的性的研究产生了一个副产品，就是通过推广这中研究到系统工程设计领域，从而加固了我们对设计理论和技巧的基本理解。针对大规模和复杂系统的系统设计理论并没有