Simulink bus usage in practice: an empirical study

Matlab/Simulink is a graphical modeling environment that has become the de facto standard for the industrial model-based development of embedded systems. Practitioners employ different structuring mechanisms to manage Simulink models' growing size and complexity. One important architectural element is the so-called bus, which can combine multiple signals into composite ones, thus, reducing a model's visual complexity. However, when and how to effectively use buses is a non-trivial design problem with several trade-offs. To date, only little guidance exists, often applied in an ad-hoc and subjective manner, leading to suboptimal designs. Using an inductive-deductive research approach, we conducted an exploratory survey among Simulink practitioners and extracted bus usage information from a corpus comprising 433 open-source Simulink models. We elicited 22 hypotheses on bus usage advantages, disadvantages, and best practices from the data, whose validity was later tested through a confirmatory survey. Our findings serve as requirements for static analysis tools and pave the way toward guidelines on bus usage in Simulink.