Ontology-based framework for the generation of interlock code with redundancy elimination

In this paper, a framework for the automatic generation of redundancy-free interlock code is proposed. The core component is represented by an ontology-based integration framework that holds the relevant information from a developed piping and instrumentation diagram (P&ID) editor as well as the PLC program where the interlocks should be added. The integration framework is mainly based on AutomationML concepts as glue model between the different internal models of the P&ID editor and the PLC programming tool. In order to enable the coexistence of manual and automatically generated interlocking code, the approach is extended by additionally applying a theorem prover. Here, the theorem prover Z3 is utilized to eliminate redundant interlock logic whereas the redundancy-free logic is then automatically added as interlock code to the IEC 61131-3 compliant program. The framework is evaluated by application to a laboratory process plant.