Journal Abbreviation : ' j. Korea Saf. Manag. Sci.' Frequency : Quarterly Doi Prefix : 10.12812/ksms ISSN : 1229-6783 (Print) / 2288-1484 (Online) Year of Launching : 1999 Publisher : Korea Safety Management & Science Indexed/Tracked/Covered By :
Formal Verification of PLC Program Safety in Manufacturing Automation System
Chang Mok Park*
*Dept. of Technology & Systems Management, Induk University
†Corresponding Author: Chang Mok Park, Dept. of Technology & Systems Management, Induk University M․P: 010-4928-6634, email: cmpark@induk.ac.kr
October 27, 2015
March 17, 2015
March 17, 2015
Abstract
In an automated industry PLC plays a central role to control the automation system. Therefore, fault free operation of PLC controlled automation system is essential in order to maximize a firm’s productivity. A prior test of control system is a practical way to check fault operations, but it is a time consuming job and can not check all possible fault operation. A formal verification of PLC program could be a best way to check all possible fault situation. Tracing the history of the study on formal verification, we found three problems, the first is that a formal representation of PLC control system is incomplete, the second is a state explosion problem and the third is that the verification result is difficult to use for the correction of control program. In this paper, we propose a transformation method to reproduce the control system correctly in formal model and efficient procedure to verify and correct the control program using verification result. To demonstrate the proposed method, we provided a suitable case study of an automation system.