Delta Modeling in IEC 61499: Expressing Control Software Variability in Cyber-Physical Production Systems

IEC 61499 is a standard for developing distributed industrial control software. It supports the configurability of the control software as the application model is platform-independent and separated from the system model that defines the hardware configuration specification. Thus, it can be used to develop control software for highly configurable Cyber-Physical Production Systems (CPPS). To address their customers’ requirements, companies that build CPPSs over time develop many variants of such production systems, typically through clone-and-own reuse, which increases engineering and maintenance efforts. Managing the control software variability in CPPSs in a systematic manner would facilitate software reuse and reduce the cost of developing and maintaining these systems. However, the IEC 61499 standard itself offers only limited capabilities for managing variability, e.g., by utilizing a library of modular components or by following certain design patterns. In this paper, we propose an approach to systematically manage IEC 61499-based control software using a (textual) delta modeling approach. Delta modeling is a prominent concept in the Software Product Line (SPL) domain for expressing and maintaining software variability. We show how our delta modeling approach can express control software variability and provide a semi-automatic control software generator. We evaluate the usability of our approach by applying it to multiple case studies as well as by performing a user study, in which control software engineers used our delta modeling approach. Our evaluation results indicate potential benefits of our delta modeling approach to implement and maintain control software through software generation.