SA-OPC-UA: Introducing Semantics to OPC-UA Application Methods

Despite recent advances in Cloud manufacturing such as the introduction of Edge components, this application area still suffers from inflexible production planning and static routing. In very dynamic scenarios such as high-speed manufacturing, more autonomy of the Edge is desired in order to enable it to react to unforeseen events. The concepts of the Semantic Web, on the other hand, allow to connect machines without human intervention. Semantic Web Services (SWS) have the potential to replace manual configuration of the control applications that connect and supervise the various manufacturing resources on the shop-floor. Several specifications exist to realize SWS; the concepts of one such specification, SAWSDL, can be rapidly incorporated into the OPC-UA specification due to the nature of the information model of OPC-UA nodes. Our approach, called Semantically Annotated OPC-UA (SA-OPC-UA), introduces the concepts of SAWSDL to the OPC-UA protocol and in particular, to the application specific methods of OPC-UA. Consequently, SA-OPC-UA enables the creation of flexible orchestration plans in a manufacturing scenario controlled by cloud Manufacturing Execution Systems (MES).