【正文】 s own Communications protocol (of the agreement ASCII), the baud rate to M bit / s (adjustable). So that can greatly increase the scope of munications so that the control system configuration more flexible and convenient. Of any kind with a serial interface peripherals, such as: printers or bar code readers, Drives, a modem (Modem), the top PCconnected, and so can be used. Users can program to develop munication protocols, the exchange of data (for example: ASCII character code), RS232 interfaces with the equipment can also be used PC / PPI cable linking the free munication munications. 安徽建筑大學(xué) 畢業(yè)設(shè)計（論文） 33 When the PC offline, under the control of the next crew, the whole system can operate normally. PC that is by control centre, mainly by the PC and laser printer po nents, using SIMATIC WINCC software platform, the allChinese interface, friendly manmachine dialogue. Managers and operators can be observed through a PC, shown in the various kinds of information to understand the present and past the icestorage operation of the automatic control system and all the parameters, and through the mouse to print equipment management and implementation tasks. WINCC software in the field of automation can be used for all the operators’ control and monitoring tasks. Can be controlled in the process of the events clearly show, and shows the current status and order records, the recorded data can show all or select summary form, or may be required for editing, printing and output statements and trends . WINCC able to control the critical situation in the early stages of the report, and the signal can be displayed on the screen, can also use sound to be felt. It supported by online help and operational guidelines to eliminate failure. WINCC a workstation can be devoted to the process control to the process so that important information not is shielded. Softwareassisted operation strategy ensures that the pro。 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。 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, 安徽建筑大學(xué) 畢業(yè)設(shè)計（論文） 32 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. 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。 IEC 61499, 1998。 PLC design criteria In modern manufacturing, systems are characterized by product and process innovation, bee customerdriven 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 realtime, therefore, giving a significant petitive edge in industrial practice. Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of puting 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 安徽建筑大學(xué) 畢業(yè)設(shè)計（論文） 31 debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999。 由于工業(yè) PLC 無論何時不可能廣泛的涉及到 MAP，生產(chǎn)廠家正在考慮專用網(wǎng)絡(luò)。如歐姆龍公司正在進(jìn)行一個有關(guān) MAP 兼容性的項目。例如，雖然當(dāng)新的生產(chǎn)自動化協(xié)議