Two diagnostic models for PLC controlled flexible manufacturing systems

The control of flexible manufacturing systems (FMS’s) is generally characterised by logical and sequential functions under the auspices of a programmable logic controller (PLC). Operational faults associated with control processes are often confusing to maintenance personnel at workshop level. This has resulted in the development of automatic diagnosis techniques. In this paper two generic diagnostic models based on the logical function chart and sequential control process of the PLC are developed. With the two complementary models, the major operational faults of PLC controlled FMS’s can be diagnosed. Application of the models to a typical FMS is presented.