This document aims to investigate how Object-Oriented Programming (OOP) can improve Programmable Logic Controllers (PLC) programming. To achieve this, a PLC project was built using the OOP approaches suggested by the International Electrotechnical Commission (IEC) 61131-3 Standard. This project was tested on a simple but realistic simulated scenario for evaluation purposes.
The text starts by exposing the history of PLC programming, it’s recent enhancements and the rise of object-oriented programming in the industry and how it compares to regular software programming, before briefly presenting the resources that support object-oriented PLC programming. Four case studies and their controlling applications are then introduced, along with examples of OOP usage. The dissertation ends with a comparison between applications designed with and without using OOP.
OOP allows the creation of a standard framework for similar groups of components, reduction of code complexity and easier and safer data management. Therefore, the result of the project was an easily customizable case scenario with “plug & play” components.
In the future, the idea is to build an HMI that can take care of the changes applied in the physical system (e.g., switching a component) without accessing the code.
Eduardo Miranda Moreira da Silva