Abstract
Programmable logic controllers (PLCs) are the most used digital systems in manufacturing industry, but there is little support for test automation of such systems. As net result, testing is mostly done manually or not at all despite the recommendations of the IEC 61131-3 Standard. Attempts to provide an automated testing framework for PLCs have been recently performed with first successful results. The most advanced and promising framework proposes an approach close to object orientation that relies on nonnative language and platform. In this article, we propose a testing library called Advanced Program Organization Unit Testing Framework written in native language, built according to the unit testing paradigm, and supporting automated testing for simple and complex scenarios of IEC 61131-3 - compliant PLCs. In this article, we present such library, discuss its performance and advantages, and illustrate its application to a real case study.