SysML Modeling of Functional and Non-functional Requirements for IEC 61131-3 Control Systems

Control software performs important roles in various branches of industry. Its complexity and importance are still growing, thus it is crucial to provide engineers with new methods to improve its quality. One of possible solutions is modeling, which could be introduced into the overall development process. The paper proposes an approach to modeling of requirements dedicated to control systems developed according to the IEC 61131-3 standard. Such a solution supports four kinds of requirements. The first group specifies expected behavior of Program Organization Units (POUs, namely programs, function blocks, functions, and classes). The other two present performance requirements oriented towards POU execution and communication between devices in Distributed Control Systems (DCSs). The last type is dedicated to displays in a Human-Machine Interface (HMI) and specifies their expected operation. The proposed approach has been introduced in the CPDev engineering environment for programming various kinds of controllers.