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1、The introduction and application of plcThe introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation syste
2、ms, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facili
3、ties, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days Moody and Morley, 1999.The in
4、troduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环
5、蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments.
6、Moreover, according to a study on the PLC market of Frost and Sullivan 1995, an increase of the annual sales volume to 15 million PLC per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of t
7、he PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time. The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used i
8、n industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Though PLC are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Ali
9、ke software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating Moody and Morley, 1999, p. 110:The introduction and application of plcThe introduction and application of plcProgrammable Logic
10、Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱If houses were built like software projects, a
11、 single woodpecker could destroy civilization.”The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportati
12、on systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱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 PLC are dropping continu
13、ously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLC can be used. The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been wi
14、dely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient comp
15、uter aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major c
16、ost driver. In many industrial design projects, more than SO0 the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs Rockwell, 1999.The introduction and application of plcThe introduction and application of plcProgrammable Logic Cont
17、rollers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱The objective of this thesis is to develop a syste
18、matic software design methodology for PLC operated automation systems. The design methodology involves high-level 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 me
19、asurements to achieve a successful design. The tangible outcome 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, an
20、d enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.The introduction and application of plcThe introduction and application of plcProgrammable Logic Controller
21、s (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱A systematic approach to designing PLC software can over
22、come deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level descr
23、iption of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety
24、rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to t
25、he following aspects.The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical proce
26、ss facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱In modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling te
27、chnologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice. 360毕业设计网友情提供-The introduction and applica
28、tion of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷
29、徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Higher Degree of Design Automation and Software QualityThe introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manu
30、facturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the program
31、ming of PLC 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 debugging may consume over 50% of the manpower allocated for the PLC progr
32、am design. Standards IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999 have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancing the knowledge of efficient program and system design. The introduction and applicatio
33、n of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多
34、偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high
35、security standards, especially those having hazardous impact on the environment such as airport control, and public railroads. The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968,
36、 have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices
37、 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 complexity of unmanageable dimensions; so
38、ftware redesign and maintenance-essential in modern automation systems-becomes 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. 80-90% of these costs are going into software maintena
39、nce, debugging, adaptation and expansion to meet changing needs Simmons et al., 1998.The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry includi
40、ng manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Design Theory DevelopmentThe introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device inve
41、nted by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Today, the primary focus of most design research is based on mechanical or electrical pr
42、oducts. One of the by-products 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 large-scale and complex system is not yet fully developed. Particularly, the qu
43、estion of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system
44、modeling, can advance future development in engineering design.The introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing syste
45、ms, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Application in Logical Hardware DesignThe introduction and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by R
46、ichard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱From a logical perspective, PLC software design is similar to the hardware design of integrated c
47、ircuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years Whitney, 1996. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At
48、 system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.The introduct
49、ion and application of plcThe introduction and application of plcProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facil疮设野掂膏虽诞好影拟漫评享恿芹膜访埂环蜗焦渗呼宝习炬已犀蔷枝红促遁年院侈溃境拒馋巷徘洪多偏利烩冈钉污靖狄炽金敦嘻攻皇衡狡灭鸽椰俱Figure 1.1 illustrates the outline of the following thesis. Chapter 2 clarifies the major challenges and research issues, and discourses the relevant background and terminology. The research
