Managing Variability and Reuse of Extra-functional Control Software in CPPS

Cyber-Physical Production Systems (CPPS) are long-living and variant-rich systems. Challenges and trends in the context of Industry 4.0 such as a high degree of customization, evolution, and different disciplines involved, e.g., mechanics, electrics/electronics and software, cause a high amount of variability. Mastering the variability of functional control software, e.g., different control variants of an actuator type, is itself a challenge in the development and reuse of CPPS software. This task becomes even more complex when considering the variability of human-machine interface (HMI) software and extra-functional software such as operating modes, diagnosis or fault handling. Moreover, the interdependencies between functional, extra-functional and HMI software pose an additional challenge for variability management and the planned reuse of these software parts. This paper illustrates the challenges in documenting the dependencies of these software parts including their variability using family models. Additionally, the current state-of-practice in industry, which was derived in questionnaires and interview studies, is shown and compared to the potential of increasing the software's reusability and thus its flexibility in the context of Industry 4.0 by concepts using the object-oriented extension of IEC 61131-3.