When different business units of an international company are responsible for the development of different parts of a large system a component-based software architecture may be a good alternative to more traditional, monolithic architectures. The new common control system, developed by ABB to replace several existing control systems, must incorporate support for a large number of I/O systems, communication interfaces, and communication protocols. An activity has therefore been started to redesign the system?s architecture, so that I/O and communication components can be implemented by different development centers around the world. This paper reports on experiences from this effort, describing the system, its current software architecture, the new component-based architecture, and the lessons learned so far.