When deciding to link or embed a composite, you should know how you want the data to be updated. Composites, especially linked composites, contain some subtle functional differences that are important to consider when developing and maintaining control strategies. Among the distinguishing characteristics of composites is the type of data it contains, which can either be structural information or parameter information.
Structural information for a composite containing a function block diagram includes all the function blocks contained in the diagram, how they are wired together, and where they are placed on the diagram. For composites containing SFCs, the structural information includes what steps and transitions are contained on the diagram, how the steps and transitions are connected together, and where the steps and transitions are placed on the diagram.
Parameter information for a composite containing a function block diagram includes all the parameter names, parameter data values (including expressions), status information, and filter settings. For composites containing SFCs, the parameter information includes step actions, step transition conditions, and module parameters.
The following figure shows the relationship of structural and parameter information for both embedded and linked composites. For a more in-depth discussion on the characteristics of embedded composites and linked composites, refer to the following two sections.
