Co-simulation settings in the master simulator

Size of the co-simulation time step

Once the slave FMU is imported in an FMI master simulation environment, the first parameter to be set is the size of the co-simulation time step, since it is the most important parameter of co-simulation in general (refer to the section The Export Tool in detail for a more detailed discussion about the principles of co-simulation).

It has to be set carefully with a good knowledge of the dynamics of all the underlying systems, not only those of the system included in the slave FMU, but also the dynamics of the systems that are modeled in the master simulation environment.

Setting a too small step size can have drastic effects on computational performances, since it yields a large number of solver steps and model evaluations. Depending on the nature of the coupled system, a too large step size could also affect the stability of the whole co-simulated system and thus the accuracy of results.

Final time

If the importing environment initializes the FMU with a stop time, this stop time is used as the final time of the Simcenter Amesim model. It means that the environment cannot schedule time steps beyond this final time. An error message is reported by the FMU if the environment tries to simulate the FMU past the final time.