VarApp: Variant Management App for IEC 61131-3 Compliant Legacy Software

Despite its many drawbacks, clone & own is still frequently used for control software development in the domain of automated Production Systems (aPSs). However, this procedure leads to a high amount of so-called legacy software variants, which are usually unmanaged and, thus, difficult to maintain or reuse. To facilitate the reuse of existing software, this paper presents a model-based approach for documentation, configuration, and derivation of IEC 61131-3 compliant control software. Thereby, the required models are stored in a NoSQL database and represent the structure and the variability of the considered aPS from a functional viewpoint. A visualization of the variability in the style of a Software Product Line, which is commonly used in the informatics domain for the development of variant-rich systems, enables the user to configure a variant and the respective IEC 61131-3 compliant control software is generated automatically through model transformations. The developed concept is evaluated with a prototypically implemented web application and the control software variants of a laboratory demonstrator. Thereby, the web application supports the integration of variants from existing legacy software into the database model.