Title :
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
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;
Conference_Titel :
Control Applications, 1992., First IEEE Conference on
Conference_Location :
Dayton, OH
Print_ISBN :
0-7803-0047-5
DOI :
10.1109/CCA.1992.269771
