Transformation Algorithm from Ladder Diagram to SFC Using Temporal Logic

Abstract

Ladder Diagram (LD) has been widely used in industries as a language for sequential controls. However, the LD can not represent sequential flows of control logics explicitly. This leads to difficulties in understanding the control logics for other engineers. To overcome this problem, Sequential Function Chart (SFC) has been proposed. As the SFC can represent the sequential flow explicitly, it is expected to be used more widely. As many knowhows have been required in the LD, it is necessary to develop a transformation algorithm from LD to SFC. In this paper, a technique to transform LD to the corresponding SFC by using Temporal Logic is proposed. In the closed loop system which consists of the controlled plant and LD, the information in the sequence including parallel path divergences is extracted to develop the transformation algorithm. An example is also shown to verify the feasiblity of the proposed algorithm.