A Petri net semantics for the PLC language Instruction List

In this paper we will describe a Petri net semantics of the PLC language Instruction List (IL) defined in [DIN EN 61131-3] (IEC 1131-3). This is a nessessary prerequisite to be able to analyse functional and especially safety requirements of IL programs. We will define a subset of IL (IL 0) and give formal definitions with reference semantics for this subset. After this the reference semantics is transformed into a Petri net model.