PyLC+: A Scalable Python Framework for Automated Translation and Testing of Industrial PLC Programs

As industrial PLC programs become more complex, automated testing and verification methods are needed to ensure their reliability and correctness. This paper presents PyLC+, a modular framework that translates PLC programs into Python, allowing for automated AI-driven test generation. PyLC+ builds upon our previous work, addressing limitations by adopting a class-based modular architecture that improves the tool’s scalability, maintainability, and extensibility. This structural refinement eliminates reliance on nested functions, facilitating the translation of large-scale, real-world PLC programs while maintaining precise use of cyclic execution. Furthermore, PyLC+ introduces automated handling of stateful FBs, ensuring compliance with IEC 61131-3 execution semantics.Additionally, the tool proposes integrating LLM-driven test generation with search-based test generation to improve the efficiency and effectiveness of testing PLC software. We tested PyLC+ in a large-scale company developing train control systems, demonstrating its efficiency and effectiveness in handling complex industrial PLC programs.