Towards an abstraction layer for PLC programming using object-oriented features of IEC61131-3 applied to motion control

We present our Abstraction Layer Object-oriented Architecture (ALOOA) and its application to Motion Control. This layer provides a higher level of abstraction than that provided by the well-known PLCOpen library. In fact, the proposed approach uses OO features (i.e. methods, inheritance, and polymorphism) which allow us to define a generic device of motion control, whose hardware-dependent implementation details are then developed with specific Function Blocks (FBs) and methods. We are currently developing and using in our software the ALOOA and its libraries. As result, we can create hardware-independent software applications. Additionally, we achieved a reuse degree of our code of about 70% and improved its maintainability. ALOOA approach could be used to simplify and/or fulfill the maintainability, life-cycle-management, and the specific-platforms-and-their-limitations challenges. Moreover, it could help the OO features to penetrate further into the PLC world.