Integrating System and Software Engineering Activities for Integrated Modular Avionics Applications

Avionics systems are complex systems that integrate hardware, communication media, have many interactions with other subsystems, within or outside of the aircraft, and for the system discussed in this presentation, integrate software that must be developed according to DO-178B guidelines. System engineering and software engineering are two engineering disciplines that are historically handled by teams with different cultures, and when their engineering processes are supported by tools, use different and incompatible tools. This often leads to a difficult collaboration, with at some point, redundant information and inconsistencies. This presentation introduces a solution, based on the SysML standard for system modeling, and on the SCADE Suite product from Esterel Technologies for the development of DO-178B certified software components. This solution, named SCADE System, allows system and software engineers to work with the right formalism for their respective domains while improving cooperation due to a unified tool framework for System and Software models, the same requirements traceability and documentation generation tools, and a synchronization mechanism for the data that are at the frontier between the two engineering domains. This solution can be the basis to develop systems that have to adhere to both functional standards, such as ARINC 653 (IMA) or ARINC 661 (CDS), and certification standards like ARP 4754 (Systems), DO-178B (Software), or DO-297 (IMA). The presentation details, in particular, how this solution can be applied in the system and software engineering processes evolving in parallel in industrial avionics projects, and how the work in the system and software engineering can be synchronized. The system and software engineering flow is demonstrated on an avionics application use case from Eurocopter. It starts with a description of the intended application functionality. A description of the IMA equipment, modules, and partitions is then provided. This is followed by a description of the application architecture together with a tabular description of the allocation of the system functions to the architecture physical components and a description of the allocation of functional data to physical messages. Finally, the software blocks are mapped to a SCADE Suite software model. This interface is the basis for synchronization between system and software engineering activities. The synchronization action shall be explicit and it can be triggered either by the system team or software team. When the software design and verification is completed, the code can be compiled and loaded on the target. ARINC 653 configuration files (IMA) and glue code can be automatically generated from scripts based on the system and software model APIs.