Service-Oriented Process Control with Grafchart and the Devices Profile for Web Services

To fulfil increasing requirements within the manufacturing sector, highly flexible and adaptable automation systems are needed. It is desirable to have one integrated approach that stretches from the process planning phase, through the implementation phase and all the way to the phase for execution of the process control logics. One promising approach is to use the concepts of service-oriented architectures within automation, here referred to as SOA-AT. As service technology, DPWS has proved to be the most suitable for realizing service based communication on device level. The paper shows how Grafchart, a graphical language aimed for sequential control applications, can support the development of DPWS applications, and how Grafchart can be used for process modelling and execution in the planning and execution phase. This constitutes a unique framework for the development and execution of SOA applications in accordance with the requirements for automatic control tasks. The paper also presents an industry-related experimental setup in which the SOA-AT concepts are demonstrated through the use of Grafchart.