Enhancing the Detector Control System of the CMS Experiment with Object Oriented Modelling

WinCC Open Architecture (WinCC OA) is used at CERN as the solution for many control system developments. This product models the process variables in structures known as data points and offers a custom procedural scripting language, called Control Language (CTRL). CTRL is also the language to program functionality of the native user interfaces (UI) and is used by the WinCC OA based CERN control system frameworks. CTRL does not support object oriented (OO) modeling by default. A lower level OO application programming interface (API) is provided, but requires significantly more expertise and development effort than CTRL. The Detector Control System group of the CMS experiment has developed CMSfwClass, a programming toolkit which adds OO behavior to the data points and CTRL. CMSfwClass reduces the semantic gap between high level software design and the application domain. It increases maintainability, encapsulation, reusability and abstraction. This paper presents the details of the implementation as well as the benefits and use cases of CMSfwClass.