【正文】 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 lowcost PLCs can be used.In general, the productivity in generating PLC is far behind pared to other domains, for instance, VLSI design, where efficient puter aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLCprogramming requires a simultaneous consideration of hardware and software. The software design bees, 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 plexity in largescale projects.The objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves highlevel 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 oute 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 overe shortings of current programming strategies that are based on the experience of the individual software developer.Three、now of PLCFrom 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 bination configuration.In the user view, a detailed analysis of the CPU39。國際電工委員會(IEC)頒布的可編程控制器標準草案中對可編程控制器作了如下的定義：可編程控制器是一種數字運算操作的電子系統(tǒng)，專為在工業(yè)環(huán)境下應用而設計。如果房子建造的像軟件過程一樣，那么僅僅一只啄木鳥就可以摧毀文明。固定式PLC包括CPU板、I/O板、顯示面板、內存塊、電源等，這些元素組合成一個不可拆卸的整體。PLC控制器比快擦型存儲器使用得更早，EPROM存儲器比快擦型存儲器也更早，快擦型存儲器必須用紫外線（UV，UltraViolet Ray）燈擦除，并在編程器上進行編程。 幾乎所有用于為PLC控制器編程的程序都擁有各種不同的選項，例如系統(tǒng)輸入/輸出（I/O線）的強制開關，程序實時跟蹤以及圖表驗證。有些較小的PLC控制器從與PLC控制器集成在一起的小電源為它們的輸入提供電壓源。 IEC 61499, 1998。而且，正在設計理論和代表計算機科學及運籌學研究的認識論結果之間構建一條橋梁，這樣的具體應該是邏輯硬件電路設計?？缮壍男阅芘c多種冗余結構，使得AK1703 ACP可以完美處理各種功能要求。目前，大部分設計研究的主要焦點都集中在機械和電子產品上。結果，程序上的延遲和資源成了生產工業(yè)過程的主要絆腳石。不同的模塊使用不同的電流量。這對于工業(yè)企業(yè)來說是非常重要的。CPU同樣關注通信, PLC控制器,操作程序的執(zhí)行,監(jiān)督記憶設置的輸入和輸出等部分的關聯(lián)性。方法論還包括一個逐步的設計過程，并且要設置一個設計規(guī)則，這樣才能為一個成功的設計提供導向和方法。而且，盡管硬件的價格在逐漸下跌，據估計，根據Frost和Sullivan對PLC市場的調查研究表明，每年銷售硬件的價格要比銷售PLC的價格（一千五百萬）至少多出八十億美元。英文資料翻譯題 目 PLC overview 英文原文資料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 puter functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, such as the advantages of cheap prices bined 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 mid1970s, the Plc has been widely used as a central processing unit microprocessor, import export module and the external circuits are used, largescale integrated circuits even when the Plc is no longer the only logical (IC) judgment functions also have data processing, PID conditioning and data munications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition : programmable controller is a digital electronic puters 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 noncontact equipment, the procedures can be changed to ch