Bani Younis, M; Fay, A.; Frey, G.: Automatic Re-Implementation of PLC Programs. atp international - Automation Technology in Practice, Oldenbourg Verlag, Vol. 1, pp. 28-32, Apr. 2008. 


The manual re-implementation of an existing PLC application onto a new PLC platform requires considerable effort, especially when programs are written in Instruction List (IL). This paper proposes a re-implementation approach for IL programs based on formal methods (here: Finite State Machines, FSMs). Starting from a given IL program, the proposed approach first automatically generates a representation of the code in the form FSMs. The FSMs serve both as a re-documentation of the code and as a starting point for the conversion into target PLC programs based on IEC 61131-3. Those parts of the control program which serve as sequence control are automatically converted into Sequential Function Charts (SFCs) compliant to IEC 61131-3. Thus, the results can easier be understood and maintained in the future.