Abstract:
In current automation world, majority of systems are designed using programmable logic controllers (PLC) under the IEC 61131-3 standard. The IEC 61131-3 standard PLCs are struggling with increasing demand for reconfigurability and flexibility in distributed control systems. The IEC 61499 standard is considered as the key of enabling distributed and intelligent control into industrial automation. However, the use of the IEC 61499 standard in the automation industry is still minimal. Although advantages of replacing legacy systems with function block controlled systems are substantial, the learning curve is quite steep and the cost of required research and development is high. Introducing the IEC 61499 standard into the IEC 61131-3 based systems provides flexibility and reconfigurability as well as a better graphical view of system designs. Therefore it is important to provide an easy migration path for existing PLC programs into IEC 61499 compliant platforms as the first step towards widespread adoption of the new standard. This research presented in this thesis proposes a new methodology of migration from IEC 61131-3 PLCs to IEC 61499 function blocks. The aim of this migration process is to recreate IEC 61131-3 applications in IEC 61499 implementations with equivalent execution behaviour. The formal model of the IEC 61131-3 standard and formal cyclical execution model is included. This method also creates a foundation for correct-by-design development tools and automatic migration between the IEC 61131-3 and the IEC 61499 standards. Formal migration rules based on ontology mappings, restoring execution model including tasks and programs scheduling and variables mapping with different access levels are also provided. A transformation engine for import PLC code in XML format, mapping from PLC ontology model to Function Block model and code generation is implemented based on an ontological knowledge base and semantic query-enhanced web rule language. This research also proposes a new approach for semantic analysis using multiple-layered ontological knowledge base and rule-based configurable engine. The semantic rules of the IEC 61499 standard are proposed.