SysML modeling of POU-oriented unit tests for IEC 61131-3 control software

Control software performs an important role in various areas in industry. It might be responsible for executing the tasks, where even a small mistake could cause serious damages, loses or could be dangerous for operators. Thus, it is necessary to ensure that the control software quality is as high as possible. There are some approaches to increase it, such as using modeling, standardized implementation, and precise testing. In this paper, the process of modeling unit tests is presented. Such tests are dedicated to Program Organization Units from solutions created according to the IEC 61131-3 standard. The proposed approach allows to model requirements with tests that verify them, a complete test behavior, as well as test suites. For this purpose, three kinds of diagrams from the SysML language are used, namely Requirement, Activity, and Block Definition Diagrams. The model is used to automatically generate templates of tests, the complete tests implementation in the CPTest+ test definition language, as well as a configuration of test suites. The proposed concept has been introduced into the CPDev engineering environment that allows to program controllers.