| Traditional PLC has contributed much to the progress of man in the domain of automatic control. But recent years, with the development of computer technique and the establishment of IEC61131-3 criterion, SoftPLC developed rapidly. Recent years, embedded system has been widely used in the field of industry control. So it's a trend to combine the embedded system and SoftPLC, SoftPLC can work in an embedded system as an embedded application programming. This thesis, starts with the introduction of embedded system and SoftPLC, and then analyses hardware and software platform of embedded SoftPLC and it's control project. Based on the result of analysis, a model of embedded SoftPLC, which includes developing system and running system, is provided. As a kernel, the thesis detailedly discusses the specific implementation of the SoftPLC based on embedded developing platform. The SoftPLC running system is designed according to the "Cycle Scan"work model of PLC. In every working cycle, SoftPLC go through three steps to run program, which include input sampling, executing user's program and output refreshing. In running system, we first gave a particular description of the hardware structure, after that, the structure of software is referred, includes the implementation of Linux system. And then we discuss how to realize the program and human machine interface (HMI) in detail. In developing system, we discuss how to realize the editor of ladder diagram. This thesis gave a test of the running system of it's real time and running capability on different platforms. Based on the test result, look forward to the development of the research and put forward what would be focused on in the future research. This thesis provides a full description of framework and detailed realization of embedded SoftPLC, and it can be very good reference in the research of the same field.
|
PDF Full Text Request