【正文】 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 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 bination configuration. In the user view, a detailed analysis of the CPU39。 ISO 157451, 1999] have been formed to fix and disseminate stateoftheart 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 ponents, and will provide methods to make largescale 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 plexity 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 plexity of unmanageable dimensions。 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。 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。 IEC611313, 1993。 Second， programming visual, simple。軟件輔助操作策略保證過(guò)程不被非法訪問(wèn)，并提供用于工業(yè)環(huán)境 中的無(wú)錯(cuò)操作。可將過(guò)程控制中發(fā)生的事件清楚地顯示出來(lái)，可顯示當(dāng)前狀態(tài)并按順序記錄，所記錄的數(shù)據(jù)可以全部顯示或選擇簡(jiǎn)要形式顯示，可連續(xù)或按要求編輯，并可輸出打印報(bào)表和趨勢(shì)圖。 當(dāng)上位機(jī)脫機(jī)時(shí)，在下位機(jī)控制下，整個(gè)系統(tǒng)能正常運(yùn)行。 5Mbit/s（可調(diào)整）。 CP2020/CPC25 特征與功能 系統(tǒng)功能：