Design recovery for relay ladder logic

Author

Falcione, Albert ; Krogh, Bruce H.

Author_Institution

Dept. of Electr. & Comput. Eng., Carnegie Mellon Univ., Pittsburgh, PA, USA

fYear

1992

Firstpage

648

Abstract

An algorithm for converting relay ladder logic (RLL) programs for programmable logic controllers (PLCs) into sequential function chart (SFC) programs is introduced. Since an SFC (a standardization of Grafcet) better represents the sequential flow of control logic, it is considerably easier to understand and modify SFC programs. Existing RLL programs are converted into SFC programs by recovering the underlying sequential control logic. This conversion of the program representation is referred to as design recovery. A basic design recovery algorithm is presented and applied to a simple RLL program for one stage of a batch chemical process. Several fundamental issues in discrete control logic representation and analysis are also identified as fertile areas for future research

Keywords

batch processing (industrial); chemical industry; formal logic; programmable controllers; sequential switching; Grafcet; PLC; RLL; batch chemical process; design recovery; discrete control logic representation; programmable logic controllers; relay ladder logic; sequential control logic; sequential function chart; Algorithm design and analysis; Automatic logic units; Chemical processes; Computer languages; Information processing; Laboratories; Logic design; Logic programming; Programmable control; Relays;

fLanguage

English

Publisher

ieee

Conference_Titel

Control Applications, 1992., First IEEE Conference on

Conference_Location

Dayton, OH

Print_ISBN

0-7803-0047-5

Type

conf

DOI

10.1109/CCA.1992.269771

Filename

269771