On the Analysis of PLC Programs: Software Quality and Code Dynamics

As a result of sudden failure in the Programmable Logic Control (PLC) controlled process, the need of diagnosis arises. Diagnosis problem plays an important role to monitor failures in PLC, used to control the whole process. Nowadays and due to the lack of the needed tools availability to perform this action automatically, it is accomplished manually. Usually, the time consuming method is used by back-tracking the failure on an actuator due to the corresponding sensors. This paper analyzes the software quality metrics and their application on the PLC programs. Aiming to implement metrics that gives predictive information about diagnosability of an Instruction List (IL) PLC programs, this could minimize the needed effort to check the program in case of mistakes. Furthermore, to get a better prediction about diagnosability, new metrics are introduced which are able to give more information about the semantics of a program. But they are not yet fully developed and have to be analyzed.