IEC 60848 GRAFCET is a standardized, graphical specification language for control functions. Because of the semiformal nature of IEC 60848, the details of specifications created with GRAFCET can be interpreted in different ways, possibly leading to faulty implementations. These ambiguities have been partially addressed in existing literature, but solved in different manners. Based on a literature review, this work aims at providing an overview of existing interpretations and, based on that, proposes a comprehensive interpretation algorithm for IEC 60848, which takes all relevant ambiguities from the literature review into account.

The graphical modeling language GRAFCET is used as a formal specification language in industrial control design. This paper proposes a structural analysis that approximates the variable values of GRAFCET to allow verification on specification level. GRAFCET has different elements resulting in concurrent behavior, which in general results in a large state space for analyses like model checking. The proposed analysis approach approximates that state space and takes into consideration the entire set of GRAFCET elements leading to concurrent behavior. The analysis consists of two parts: We present an algorithm analyzing concurrent steps to approximate the step variables and we adapt analysis means from the field of Petri nets to approximate internal and output variables. The proposed approach is evaluated using an industrial-sized example to demonstrate that the analysis is capable of verifying behavioral errors and is not limited by the specification size of practical plants.

Model checking of GRAFCET, an IEC standardized specification language, is typically performed by a translation of GRAFCET into a different (target) formalism. However, analyzing instances of considerable sizes quickly becomes unfeasible due to the state space explosion problem. We propose three techniques to reduce a GRAFCET instance depending on the property to be evaluated, resulting in a smaller state space. These techniques can be employed, even in combination, before transformation into a formalism suitable for model checking.

The graphical modeling language GRAFCET is used as a formal specification language in industrial control design. This paper proposes a static analysis approach based on the control flow of GRAFCET using abstract interpretation to allow verification on specification level. GRAFCET has different elements leading to concurrent behavior, which in general results in a large state space. To get precise results and reduce the state space, we propose an analysis suitable for GRAFCET instances without concurrent behavior. We point out how to check for the absence of concurrency and present a flow-sensitive analysis for these GRAFCET instances. The proposed approach is evaluated on an industrial-sized example.

Automatic test suite generation is an established technique used to generate test suites adhering to structural coverage metrics of PLC software. In order to reduce redundancy in the test suite generation after a structural reconfiguration to the PLC software has occurred, reusable summaries of program parts should be employed. This paper presents a combination of state-of-the-art symbolic execution and static analysis algorithms for test suite generation and summary reuse. The general rationale is to improve efficiency by not doing redundant work. For this purpose, summaries of function blocks are cached and reused to benefit from the previous analysis. As code untouched from reconfigurations will result in equivalent path conditions summaries can aid in speeding up regression testing. The proto-typical implementations of several techniques are evaluated and compared using selected domain-specific benchmarks showing the ineffectiveness of using summarization during test suite generation for reconfigurable logic control software.