关于PLC的毕业设计外文翻译

毕业设计（外文翻译）英文题目The development and future of PLC

中文题目 PLC的发展和未来

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The development and future of PLC

Part 1 PLC overview

Programmable 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.

Part 2 History of PLC

Programmable 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

`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 of the manpower allocated for the control system design and installation is scheduled for testing

and debugging PLC programs.

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.

The 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.

Part 3 Now of PLC

From the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory block, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, the power modules, bottom or a frame, these modules can be according to certain rules combination configuration.

In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interprets the instruction and executes instructions. But the pace of work by shock signal control.

Unit work under the controller command used in a digital or logic operation.In computing and storage register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters for PLC , its determines the PLC speed of work, IO PLC number and software capacity, so limits to control size.

Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output.

System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.

User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either a s “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.

PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs).

Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines),

program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.

Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 V AC. On some PLC controllers you’ll find electrical supply as a separate module. Those are us ually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current.

This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.

Part 4 PLC design criteria

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.

In 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.

Studies 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.

The 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.

Today, 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.

From 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.

Part 5 AK 1703 ACP

Following the principle of our product development, AK 1703 ACP has high functionality and flexibility, through the implementation of innovative and reliable technologies, on the stable basis of a reliable product platform.

For this, the system concept ACP (Automation, Control and Protection) creates the technological preconditions. Balanced functionality permits the flexible combination of automation, telecontrol and communication tasks. Complemented with the scalable

performance and various redundancy configurations, an optimal adaptation to the respective requirements of the process is achieved.

AK 1703 ACP is thus perfectly suitable for automation with integrated telecontrol technology as:

? Telecontrol substation or central device

? Automation unit with autonomous functional groups

? Data node, station control device, front-end or gateway

? With local or remote peripherals

? For rear panel installation or 19 inch assembly

? Branch-neutral product, therefore versatile fields of application and high product stability

? Versatile communication

? Easy engineering

? Plug & play for spare parts

? Open system architecture

? Scalable redundancy

? The intelligent terminal - TM 1703

The Base Unit AK 1703 ACP with Peripheral Elements has one basic system element CP-2010/CPC25 (Master control element) and CP-2012/PCCE25 (Processing and communication element) ,one bus line with max. 16 peripheral elements can be connected.

CP-2010/CPC25 Features and Functions

System Functions:

? Central element,coordinating al l system services

Central hub function for all connected basic system elements

? Time management

Central clock of the automation unit

Setting and keeping the own clock`s time with a resolution of 10ms

Synchronization via serid communication via LAN or local

? Redundancy

V oting and change-over for redundant processing and communication elements of the own automation unit

Supports voting and change-over by an external SCA-RS redundancy switch

Supports applicational voting and change-over by an external system,e.g.a control system

? SAT TOLLBOX|| connection

Storing firmware and parameters on a Flash Card

Communication:

? Communication via installable protocol elements to any superior or subordinate automation unit

? Automatic data flow routing

? Priority based data transmission (priority control)

? Own circular buffer and process image for each connected station(data keeping)

? Redundant communication routes

Communication with redundant remote stations

? Special application specific functions for dial-up traffic

Test if stations are reachable

Process Peripherals:

? T ransmission of spontaneous information objects from and to peripheral elements, via the serial Ax 1703 peripheral bus

Functions for Automation:

? Open-/closed-loop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC 61131-3,https://www.360docs.net/doc/e318838888.html,ing function diagram technology

512KB for user program

Approx 50.000 variables and signals,2.000 of them retained

Cycle of 10ms or a multiple thereof

Online test

Loadable without service interruption

? Redundant open-/closed-loop control functions

Synchronization via redundancy link

Transmission of periodic process information between the open-/closed-loop control function and the peripheral elements,via the serial Ax 1703 peripheral bus.

PLC的发展和未来

一、PLC概述

可编程控制器是60年代末在美国首先出现的，当时叫可编程逻辑控制器PLC （Programmable Logic Controller），目的是用来取代继电器。以执行逻辑判断、计时、计数等顺序控制功能。提出PLC概念的是美国通用汽车公司。PLC的基本设计思想是把计算机功能完善、灵活、通用等优点和继电器控制系统的简单易懂、操作方便、价格便宜等优点结合起来，控制器的硬件是标准的、通用的。根据实际应用对象，将控制内容编成软件写入控制器的用户程序存储器内,使控制器和被控对象连接方便。

70年代中期以后，PLC已广泛地使用微处理器作为中央处理器，输入输出模块和外围电路也都采用了中、大规模甚至超大规模的集成电路，这时的PLC已不再是仅有逻辑(Logic)判断功能，还同时具有数据处理、PID调节和数据通信功能。国际电工委员会(IEC)颁布的可编程控制器标准草案中对可编程控制器作了如下的定义：可编程控制器是一种数字运算操作的电子系统，专为在工业环境下应用而设计。它采用了可编程序的存储器，用来在其内部存储执行逻辑运算，顺序控制、定时、计数和算术运算等操作的指令，并通过数字式和模拟式的输入和输出，控制各种类型的机械或生产过程。可编程控制器及其有关外围设备，易于与工业控制系统联成一个整体，易于扩充其功能的设计。

可编程控制器对用户来说，是一种无触点设备，改变程序即可改变生产工艺。目前，可编程控制器已成为工厂自动化的强有力工具，得到了广泛的普及推广应用。

可编程控制器是面向用户的专用工业控制计算机，具有许多明显的特点。

二、PLC的历史

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，多数人力分配给了控制系统设计和安装，并且他们被要求对PLC进行程序测试和错误排除。

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。

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。

三、现今的PLC

从结构上分，PLC分为固定式和模块式两种。固定式PLC包括CPU板、I/O板、显示面板、内存块、电源等，这些元素组合成一个不可拆卸的整体。模块式PLC包括CPU模块、I/O模块、内存、电源模块、底板或机架，这些模块可以按照一定规则组合配置。

在使用者看来，不必要详细分析CPU的内部电路，但对各部分的工作机制还是应有足够的理解。CPU的控制器控制CPU工作，由它读取指令、解释指令及执行指

令。但工作节奏由震荡信号控制。

运算器用于进行数字或逻辑运算，在控制器指挥下工作。寄存器参与运算，并存储运算的中间结果，它也是在控制器指挥下工作。CPU速度和内存容量是PLC的重要参数，它们决定着PLC的工作速度，IO数量及软件容量等，因此限制着控制规模。

中央处理器(CPU)是PLC控制器的大脑。通常CPU本身就是一个微控制器。起先是8位微控制器例如8051,现在发展为16位和32位微控制器。你会发现大部分由日本制造商制造的PLC中是日立和Fujicu的微控制器,西门子的微控制器多应用在欧洲的PLC中,摩托罗拉生产的微控制器则独占美国市场。CPU同样关注通信, PLC控制器,操作程序的执行,监督记忆设置的输入和输出等部分的关联性。

PLC使用系统存储器（现在大部分采用闪存技术了）用于过程控制系统。除了这个操作系统之外，它还包括一个由梯形图翻译成而进制形式的用户程序。快擦型存储器（FLASH memory）的内容只有在改变用户程序的时候可以被改变。PLC控制器比快擦型存储器使用得更早，EPROM存储器比快擦型存储器也更早，快擦型存储器必须用紫外线（UV，Ultra-Violet Ray）灯擦除，并在编程器上进行编程。由于快擦型存储器技术的应用，使得这个过程大大缩短了。在应用程序开发中，通过一个串行电缆可以对程序存储器进行重新编程。

用户存储器被分成具有特殊功能的块。一部分存储器用来存储输入和输出状态。一个输入的实际状态存储状态存储在专用存储器位上，为“1”或者“0”。每一个输入和输出在存储器中都有一个相应的位。另外一部分存储器用来存储用户程序中的变量的内容。例如，定时器值，或者记数器值存放在存储器的这个部分。

PLC控制器可以通过计算机（通常方式）重新编程，但是也可以通过人工编程器9控制台）编程。实际上，这意味着，如果你有编程所需要的软件，早期PLC控制器可以通过计算机进行编程。今天的传输计算机是工厂自己对PLC控制器进行重新编程的理想设备。这对于工业企业来说是非常重要的。一旦系统修改结束，将正确的程序重新读入PLC控制器也是非常重要的。定期检查PLC中的程序是否改变是非常好的事情。这有助于避免车间发生危险情况（一些汽车制造商已经建立了通信网络，可以定期检查PLC中的程序，以保证运行的程序都是正确的）。

几乎所有用于为PLC控制器编程的程序都拥有各种不同的选项，例如系统输入/输出（I/O线）的强制开关，程序实时跟踪以及图表验证。图表验证对于理解、定义失败和故障非常必要。程序员可以添加标记，书日和输出设备名称，以及对于查找错误或者对于系统维护很有用的注释。添加注释和标记可以使技术人员（不仅仅是开发人员）很快理解梯形图。注释和标记甚至还可以准确地引用零件号，如果需要

更换零件的话。这将加快由于损坏零件而引起的任何问题的修理速度。响应的旧方法是这样的，开发系统的人必须保护这个程序，他旁边再没有人知道系统是怎样完成的。正确的、备有证明文件的梯形图使任何技术人员都能彻底理解系统的功能。

电源是为中央处理单元提供电源的。大部分PLC控制器的工作电压为24VDC或者220V AC。在有些PLC控制器上，你可以看见作为独立模块的电源。用户必须确定从I/O模块取出多大电流来保证电源提供适当的电流。不同的模块使用不同的电流量。

该电源一般不用于启动外部输入或输出。用户必须提供独立的电源来启动PLC 控制器的输入和输出，因为这样可以保证PLC控制器的所谓“纯电源”。使用纯电源意味着工业环境中的电源不会严重影响它。有些较小的PLC控制器从与PLC控制器集成在一起的小电源为它们的输入提供电压源。

四、PLC的设计标准

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，为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。

在现代制造业中，系统是用过程和结果的革新来描述的，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。

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（ＰＬＣ）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“ＳＴＡＴＥ－ＯＦ－ＴＨＥ－ＡＲＴ”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。

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（ＰＬＣ）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。

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成熟。尤其是，对如何简化一个繁冗而复杂的设计任务这一问题，仍然没有被科学的处理。而且，正在设计理论和代表计算机科学及运筹学研究的认识论结果之间构建一条桥梁，这样的具体应该是逻辑硬件电路设计。

从逻辑学的角度来看，可编程逻辑控制器（PLC）的软件设计类似与集成电路的硬件设计。现代超大规模集成电路设计（Very Large Scale Integration--VLSI）是及其复杂的，一个集成电路一般有几百万个晶体管，而且产品开发周期大都三年左右。设计过程一般都分成局部功能块设计和系统设计两个阶段。在局部功能块设计阶段，单个功能将被设计出来，并予以验证。在系统设计阶段，所有功能块都将被整合起来，整个系统行为特性和功能将会通过仿真形式加以测试。一般来说，所有部分都完全的验证是不可能的。因此，统计学可以作为可编程逻辑控制器（PLC）设计的一个例子，并有可能影响逻辑硬件设计。

五、AK 1703 ACP

AK 1703 ACP凭借着一贯创新的精神与稳定的技术，在以稳定为基础的产品平台中，拥有高级的功能性和适应性。

ACP（自动化，控制和保护）系统概念保证了AK 1703 ACP功能的实现。稳定

的功能性使得自动化控制，远程控制和通信协议三者完美结合。可升级的性能与多种冗余结构，使得AK1703 ACP可以完美处理各种功能要求。

AK 1703 ACP拥有适合现代化自动控制的综合的远程控制技术：

?水电站远程控制与中控设备

?拥有自治功能的自动控制单元

?数据节点, 设备控制站, 尖端科技

?拥有现场或远程外围设备

?为后面板安装而设计的19英寸设备

?专为多种现场应用和高产品要求设计的中间产品

?多种通信手段

?简洁的编程

?唯一的设备插座

?开放型系统体系结构

?可升级的冗余

?智能终端- TM 1703

AK 1703 ACP基本外部设备原件拥有两个基本系统原件CP-2010/CPC25（主控原件）和CP-2012/PCCE25（处理和通信原件），一个总线最多可以连接16个外围设备原件。

CP-2010/CPC25 特征与功能

系统功能：

?核心元件，协调所有系统功能

连接所有基本功能原件的中心站点

?时间管理

自动控制单元的中控时钟

设定并保持自身时钟的时间，分辨率为10ms

通过互联网或当地的服务通信进行同步

?冗余

在处理与通信中为自动控制单元选择并转变冗余单元

通过SCA-RS外部冗余开关支持选择与转变功能

通过外接系统实现选择与支持,例如控制系统

?与SAT TOLLBOX||连接

在闪存卡里存储固件和参数

通信：

?通过相应的协议原件与高级或附属自动控制单元进行通信

?为数据流自动选择路径

?优先基本数据的传输(优先级控制)

?为每个联检站设立自己的循环缓冲器和处理信息(数据保持)

?为冗余通信提供路径

与对方站的冗余进行通信

?通过拨号上网方式对特殊应用实施特殊功能

为可进行冗余的站点进行测试

具有处理功能的外围设备：

?通过Ax 1703外围设备串口总线自发地将信息传输到外围设备单元自动控制功能：

?通过CAEX+按照IEC 61131-3协议创建的可自由定义的拥有开闭环控制功能的用户程序

512KB的用户程序空间

大约50000个可变信号源,2000个常用信号源

10ms的循环时间

网上测试

可随时下载

?冗余的开闭环功能控制

通过冗余线路进行同步

通过Ax 1703外围设备串口总线在开闭环控制功能与外围接口单元之间不断传输处理信息。