【導讀】以執(zhí)行邏輯判斷、計時、計數等順序控制功能。提出PLC概念的是美國通用汽車公司。價格便宜等優(yōu)點結合起來，控制器的硬件是標準的、通用的。根據實際應用對象，將?？刂苾热菥幊绍浖懭肟刂破鞯挠脩舫绦虼鎯ζ鲀?使控制器和被控對象連接方便。邏輯判斷功能，還同時具有數據處理、PID調節(jié)和數據通信功能。可編程控制器及其有關外圍設備，易于與工業(yè)控制系統(tǒng)聯成一個整體，易于擴。充其功能的設計?？删幊炭刂破鲗τ脩魜碚f，是一種無觸點設備，改變程序即可改變生產工藝。前，可編程控制器已成為工廠自動化的強有力工具，得到了廣泛的普及推廣應用。可編程控制器是面向用戶的專用工業(yè)控制計算機，具有許多明顯的特點。雖然PLC廣泛應用于工業(yè)控制中，PLC控制系統(tǒng)的程序依然和語法有關。PLC不需要使用目前的以軟件設計為基礎軟件工程。他們被要求對PLC進行程序測試和錯誤排除。器技術的應用，使得這個過程大大縮短了。

　　

【正文】 the flexibility of modern automation systems add plexity to the program design process. Consequently, the lifecycle cost of software is a permanently growing fraction of the total cost. 8090% 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 byproducts 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 largescale and plex system is not yet fully developed. Particularly, the question of how to simplify a plicated or plex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outes of formal representations in puter 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 plex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a ponent design and a system design stage. At ponent design stage, single functions are designed and verified. At system design stage, ponents are aggregated and the whole system behavior and functionality is tested through simulation. In general, a plete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design. Five、 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 bination of automation, telecontrol and munication 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, frontend or gateway ? With local or remote peripherals ? For rear panel installation or 19 inch assembly ? Branchneutral product, therefore versatile fields of application and high product stability ? Versatile munication ? Easy engineering ? Plug amp。 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 CP2020/CPC25 (Master control element) and CP2020/PCCE25 (Processing and munication element) ,one bus line with max. 16 peripheral elements can be connected. CP2020/CPC25 Features and Functions System Functions: ? Central element,coordinating all 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 munication via LAN or local ? Redundancy Voting and changeover for redundant processing and munication elements of the own automation unit Supports voting and changeover by an external SCARS redundancy switch Supports applicational voting and changeover by an external system, 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 munication routes Communication with redundant remote stations ? Special application specific functions for dialup traffic Test if stations are reachable Process Peripherals: ? Transmission of spontaneous information objects from and to peripheral elements, via the serial Ax 1703 peripheral bus Functions for Automation: ? Open/closedloop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC 611313, function diagram technology 512KB for user program Approx variables and signals, of them retained Cycle of 10ms or a multiple thereof Online test Loadable without service interruption ? Redundant open/closedloop control functions Synchronization via redundancy link Transmission of periodic process information between the open/closedloop control function and the peripheral elements,via the serial Ax 1703 peripheral bus. Six、 SIEMENS PLC SIMATIC S7300 series PLC applied to all walks of life and various occasions in the detection, monitoring and control of automation, its power to both the independent operation of, or connected to a work able to achieve plex control. The photoelectric products with isolation, high electromagic patibility。 have high industrial applicability, allowing the ambient temperature of 60 ℃ 。 has strong antijamming and antivibration and impact resistance, so in a harsh working environment has been widely Applications. I also mean freedom of munication S7300 type PLC39。 s a very unique feature, which allows S7300PLC can deal openly with any other munications equipment, munications controller,