Comparing the object-oriented extension with the classical IEC 61131-3 regarding reusability and understandability - a case study

Due to high time pressure and rising complexity in industrial automation, “new programming methodologies are necessary in order to increase software quality and reuse” [1]. The object-oriented extension of the International Electrotechnical Commission (IEC) 61131-3 standard is one of those new methodologies and one benefit of object-oriented programming in general, is more efficient reuse of code [2]. Nevertheless, it has to be evaluated whether this is also the case in the field of industrial automation. In this paper, a comparison between the functional and the object-oriented programming paradigm of the IEC 61131-3 is conducted regarding reusability and understandability. This is done by applying software measures on an application example and by conducting an expert consultation. As a result, tendencies of advantages and disadvantages of the object-oriented extension are pointed out.