UNIFIED LOGICAL MODEL TO IDENTIFY FAULTS IN A PLC CONTROLLED MANUFACTURING SYSTEM

摘要

In this paper, we present a novel approach that can identify operational faults associated with control process by using logdata records of the PLC program signals. The proposed approach automatically creates a logical model of the PLC controlprocess, called the unified logical model and then utilizes that model to detect faults. The unified logical model includes thesignal-state logical models of the devices and the relational logical models of the device groups. The signal-state logicalmodel is designed to depict the device behavior, and the relational logical model is designed to describe the relationshipbetween the dependent devices. The proposed approach automatically generates the unified logical model from the PLCsignal log data records and employs a hash table based model indexing and fault searching scheme to identify the faults in themanufacturing system. Experimental results show that the proposed model can be utilized to detect the faults effectively.