Mechatronic products consist of solutions from disparate engineering disciplines. As a consequence, the respective "mechatronic design process" has to comply with the integration of these disciplines. However, there is a critical lack of tools supporting the interdisciplinary aspects during the development process of mechatronic products, especially in the conceptual design phase. System-level models can remedy this unsatisfactory situation and allow for a holistic view on complex systems. The graphical modelling language SysML offers the possibility of developing useful system-level models.