Supporting troubleshooting in machine and plant manufacturing by backstepping of PLC-control software

摘要

Inreasingly flexible production systems realize functions using a combination of versatile sensors and actuators with complex control software. Hence, quality control of software and debugging of sporadic and difficult to find errors is becoming more and more expensive. Therefore a method to monitor and replay the behavious of the system would be highly beneficial. For the realization of a PLC-based "flight recorder" for machines or plants, technical as well as industrial requirements are analyzed. Interviews conducted in two representative machine and plant manufacturers allow the derivation of a comprehensive set of diverse use cases, which could be used as benchmark set for similar concepts in the future. Based on the use cases, two different concepts for the recorder functionality were developed, prototypically implemented, and tested according to the machine and plant manufacturers’ requirements. New programming language elements, necessary for the implementation of this functionality like an operator to identify the actual running task and the possibility to control a code dump form within the program have already found their way into the public software development environment (IDE) of CODESYS. After an evaluation using a real laboratory plant, the concepts were iteratively improved. Finally, insights of remaining research challenges or beneficial future applications for the developed methods are given.