A Method for Extraction of Function Modules of Sequential Control Programs Based on Structure Analysis

Abstract

In this paper, a method to extract function modules from sequential control programs is proposed. A hierarchical structure of a given sequential program can be found by using association graph. If some or more variables are connected each other (strongly connected), the layered structure is not easy to find. Thus, based on the concept of Markov chain, the importance of variables can be conducted. We propose a new method to divide unclear layered variables in more details. An illustrative example of a tank control program is shown as an application of the proposed method.