PLC-automata: a new class of implementable real-time automata
We introduce PLC-automata as a new class of automata which are tailored to deal with real-time properties of programmable logic controllers (PLCs). These devices are often used in industrial practice to solve controlling problems. Nevertheless, PLC-automata are not restricted to PLCs, but can be seen as a model for all polling systems. A semantics in an appropriate real-time temporal logic (duration calculus) is given and an implementation schema that fits the semantics is presented in a programming language for PLCs, A case study is used to demonstrate the suitability of this approach. We define several parallel composition operators, and present an alternative semantics in terms of timed automats for which model-checkers are available. (C) 2001 Elsevier Science B.V. All rights reserved.
plc duration calculus real time specification formal methods