Behavioural Models for FMI Co-simulations

Simulation is a favoured technique for analysis of cyberphysical systems. With their increase in complexity, co-simulation, which involves the coordinated use of heterogeneous models and tools, has become widespread. An industry standard, FMI, has been developed to support orchestration; we provide the first behavioural semantics of FMI. We use the state-rich process algebra, Circus, to present our modelling approach, and indicate how models can be automatically generated from a description of the individual simulations and their dependencies. We illustrate the work using three algorithms for orchestration. A stateless version of the models can be verified using model checking via translation to CSP. With that, we can prove important properties of these algorithms, like termination and determinism, for example. We also show that the example provided in the FMI standard is not a valid algorithm.