Execution Engine Logic
The logic of the Execution Engine includes the OPC UA server of the Execution Engine, which in turn, features the Execution Engine Data Object (1 in Figure 1). Since the DataObject provides all input and output parameter for processes, corresponding OPC UA data types are required for the server (2 in Figure 1). Here, the Execution Engine provides an interface to generate the corresponding Data Types. Tasks (3 in Figure 1) and Service Results (5 in Figure 1) are added and remove from the Data Object as described in Execution Engine Data Object. Lastly, the Execution Engine receives notification about the completion of service executions (4 in Figure 1) and transmits them to the Dispatcher, which in turn can trigger transitions of the process control and thus, schedule further services. Further information regarding the interaction between Execution Engine, Dispatcher and the Control interface can be found in section Service Dispatcher Interaction.
Figure 1: Functional entities of the Execution Engine Logic