【正文】 software redesign and maintenanceessential in modern automation systemsbees 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 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。 THE INTRODUCE OF PLC ONE、 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 change production processes. The programmable controller has bee a powerful tool for factory automation, widely popular replication. Programmable controller is useroriented industries dedicated control puter, with many distinctive features. First, high reliability, antiinterference capability。 WINCC軟件在自動化領域中可用于所有的操作員控制和監(jiān)控任務。 自由通訊口方式也是 S7300型 PLC的一個很有特色的功能，它使 S7300型 PLC可以與任何通訊協(xié)議公開的其它設備、控制器進行通訊，即 S7 300型 PLC可以由用戶自己定義通訊協(xié)議（例 ASCII協(xié)議），波特率為 1。 五、 AK 1703 ACP AK 1703 ACP憑借著一貫創(chuàng)新的精神與穩(wěn)定的技術，在以穩(wěn)定為基礎的產品平臺中，擁有高級的功能性和適應性。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。尤其是，可編程邏輯控制器（ＰＬＣ）程序設計從二十五年前的兩條主線，發(fā)展到現(xiàn)在的成千上萬條。 IEC 61499