Reuse Assessment of IEC 61131-3 Control Software Modules Using MEtrics - An Industrial Case Study

In the automated Production Systems (aPS) domain, companies need to continuously decrease their systems' development times while maintaining quality to stay globally competitive. Industry 4.0 imposes additional boundary conditions, e.g., a high degree of customization, that need to be met by aPS, which frequently have to be adapted to changing requirements during their long life cycles. Since control software implements an increasing share of aPS functionality, reusing well-tested software modules can significantly contribute to saving development time and increasing its comprehensibility and maintainability. However, planned reuse of control software modules still represents a major challenge in practice, e.g., the data exchange between software modules causes dependencies, which are often not directly visible and, thus, hinder reuse. This paper presents a metric-based concept for assessing the reusability of control software modules, focusing on different implementation types of indirect data exchange. Depending on company-specific boundary conditions, the approach can be integrated at various development process steps for continuous or one-time reuse assessment. The concept has been developed and evaluated with two industrial software projects and continuous feedback from domain experts.