Acausal (physical) modeling can be advantageously used to construct dynamic models, which are legible and easily modifiable for user. Even highly complex models can be easily assembled and the model remains clear. The most widespread language for acausal modeling is Modelica. Unfortunately Matlab/Simulink does not support Modelica language and that is why FMUtoolbox for Matlab/Simulink was established. It adds possibility to simulate Functional Mock-Up Units (exported Modelica models) to Matlab/Simulink environment. FMUtoolbox was practically proved during verification of control algorithms for stepper motor and in the design of heat pump control.