Modularization Guidelines to support Control Software Variability in IEC 61499

In the field of Cyber-Physical Production System (CPPS), a substantial number of control software components are integrated with legacy software. This legacy control software has existed in industries for decades and faces maintenance problems due to sub-optimal tool support. Consequently, rigid software structures have emerged, making maintenance difficult and necessitating better support for managing variability. These legacy systems contain an enormous volume of control software, making it impractical to transform manually in terms of variability management. Additionally, there is a growing demand for variability to accommodate to customer-specific requirements. Control software must be flexible and modular enough to fulfill diverse project-specific needs. Guidelines are required to assist control system engineers in determining which control software components must be refactored and which can be left unchanged. We investigated legacy control software from industrial use cases, identified problem areas, and gathered lessons learned. These lessons have been translated into guidelines for future control software modularization. Hence, in this paper, we present a set of guidelines aimed at modularizing IEC 61499 control software, specifically focusing on enhancing control software variability for variability-intensive CPPS.