An Empirical Investigation of Requirements Engineering and Testing Utilizing EARS Notation in PLC Programs

Abstract Regulatory standards for engineering safety-critical systems often demand both traceable requirements and specification-based testing, during development. Requirements are often written in natural language, yet for specification purposes, this may be supplemented by formal or semi-formal descriptions, to increase clarity. However, the choice of notation of the latter is often constrained by the designers’ training, skills, and preferences. The Easy Approach to Requirements Syntax (EARS) addresses the inherent imprecision of natural language requirements concerning potential ambiguity and lack of accuracy. This paper investigates requirements specification using EARS, and specification-based testing of embedded software written in the IEC 61131-3 language, a programming standard for developing programmable logic controllers (PLC). Further, we study, utilizing an experiment, how human participants translate natural language requirements into EARS and how they use the latter to test PLC software. We report our observations during the experiments, including the type of EARS patterns that participants use to structure natural language requirements and challenges during the specification phase, and present the results of testing based on EARS-formalized requirements in real-world industrial settings.