The Functional Mock-up Interface (FMI) (Blochwitz et al., 2012) has gained momentum in simulation of dynamical systems and in exchanging dynamic simulation models between tools. The standard has proven to be highly successful as it fills a gap where there were costly custom integrations before. The open source tools PyFMI1 together with Assimulo (Andersson et al., 2015) provide a solid foundation for performing simulations and experiments on single Functional Mock-up Units (FMUs).