| At present, emulation configuration software has had many years of development history in our country which is in a relatively stable stage. But as the user has more and more diverse requirements, it is difficult that a manufacturer can satisfy all the needs of users. So the manufacturers need to devote lots of energy to make the product according to the requirements of customers. Along with international standard IEC61131-3 is more and more widely used in PLC system configuration software, some distributed control system (DCS) manufacturers, domestic or foreign, started to notice the big significance of using this international standard on DCS system, and applied IEC61131-3 to their DCS system configuration software.LD is used commonly because it is intuitive and easy to understand. And considering the simulation supporting platform STAR-90 can not achieve Ladder-diagram configuration, the task of this topic is researching the execution sequence theory of Ladder-diagram, designing and developing Ladder-diagram configuration simulation platform based on IEC61131-3.Firstly, the topic background is stated. Secondly, design its overall structure frame. In the process of the system development, take the software engineering design ideas as a guide, use object-oriented design method to get the function demands of software. Three major modules of the platform are stressed, including research of Ladder-diagram execution sequence, Ladder-diagram configuration editor and Ladder-diagram simulation driver. The components graphical symbols and intuitive and lifelike Ladder-diagram edit environment is devised. Ladder-diagram execution equals to the number of pathways.And in order to improve Ladder-diagram efficiency, this system adopts the minimum path method. As a result, the expected object code which is STAR-90 original AND or OR module is obtained after conversion, the simulation driver is realized.The example shows that this system is feasible and effective, has extensive practical value. |
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