This paper presents and evaluates the Boundary Diagram Tool for change impact analysis of large Simulink designs of embedded systems. In our previous work, we developed the Reach/Coreach Tool for model slicing within a single Simulink model. The current work extends the Reach/Coreach Tool to trace the impact of model changes through multiple models comprising an embedded system, including network interfaces. The change impact analysis results are represented using various diagrams motivated by industrial needs. Several techniques are used to improve understanding of impact analyses of large industrial systems. The tool has been integrated into the software development process of a large automotive OEM (Original Equipment Manufacturer) to support the following activities: change request analysis and evaluation, implementation, verification and integration. The tool also aids impact analyses required for compliance with functional safety standards. The tool’s effectiveness has been demonstrated on production-scale models.

In the Matlab Simulink environment, systems can be modelled using Simulink block diagrams and Stateflow state charts. While stateful logic is more naturally modelled using Stateflow, in practice complex block diagrams are often used instead, resulting in models that are hard to understand and maintain. In order to improve the maintainability and understandability of large industrial models, this paper presents a strategy for refactoring Simulink block diagrams implementing stateful logic into functionally equivalent Stateflow state charts that more naturally represent the intended behaviour. To bridge the gap between the syntax of block diagrams and state charts, Mealy machines represented by tabular expressions are used as an intermediate representation. The compositional language of block diagrams is used to combine tables modelling individual blocks into a table for the entire block diagram which describes the high level state machine encoded in the Simulink subsystem. A prototype tool that performs the translation from Simulink to Stateflow automatically is discussed.