Development and evaluation of metrics for assessing the maturity of PLC software library modules based on their change history

Abstract

Lack of maturity indicators in control software library modules hinders its reuse by application engineers and start-up technicians. For this reason, this thesis aims to develop a maturity metric for function blocks written in the IEC 61131-3 programming language Structured Text based on the criticality of the changes performed throughout their evolution process. It serves as an indicator of the potential errors introduced in the source code due to the criticality of the changes made between one version and another. Therefore, it not only assists in the reuse of these modules, but also indicates those that require more testing since they have a greater risk of containing faults. The results are evaluated in collaboration with an industrial partner company which has provided several programmable logic controller software libraries containing function blocks of different size, functionality and complexity. In addition, an automatic implementation of the maturity metric is developed and a visualization of the results is designed with the aim of facilitating its integration into the industrial partner company’s version management system.