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Bachelor thesis:Tool for comparison of files of PLC programming and configuration software packages ( PDF )
Author:Nedvěd Miroslav
Supervisor:Ing. Pavel Vrba Ph.D.
Keywords:
Abstract:Goal of this work is to create a tool that will be able to compare two projects created in the development environment RSLogix5000 used for PLC programming. The project contains definitions of tags and programs written in ladder diagram of IEC61131 standard. The tool finds differences between two projects and presents them to the user. First part of the presented tool compares similarity of an XML structure by using the information about the XML scheme. Second part of the tool compares textual representation of ladder diagrams. Lines without changes are matched as first by using method for finding the longest common substrings to find the same blocks of code. The unmatched lines are parsed into the object-structure containing list of elementary instructions to compute the similarity level. Last step is selecting the most similar common subsequence of instructions. Algorithm used in the first part is much faster than commonly used algorithms for XML comparison, because the XML scheme is used and attributes Name are used as identifiers. Results of algorithm that is used in second part are very similar to differences that human can find and because unchanged rows were selected at first, it is very fast as well. The proposed tool presents differences in a graphical form to the user. The results of comparison are presented in the same form as in RSLogix5000 and thus provide more useful information to the user than general text comparison tools. The proposed tool is also much more rich than a comparison tool RSLogix Compare provided in the standart RSLogix5000 instalation. The tool will be very usefull for programmers of industrial systems from Rockwell Automation company.
Submited:May 2014
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