In a module class the parameter Properties dialog (including dialogs for the parameters of contained function blocks) contains a check box labeled Allow instance value to be configured. When this check box is selected you can edit the value of the parameter in any instance of the class. When the check box is selected, the link to instances of the class for that parameter are broken — subsequent changes at the class level do not propagate to the instances unless the Use default value from library check box is selected in the instance. Editing configurable parameters in a module instance has no effect on the module class.
At the module class level, the Allow instance value to be configured check box is in one of the following:
Selectable (not grayed out) — Select this check box to allow the value of this parameter to be changed in a module instance. In the Instance dialog, the Use default value from library object check box appears and is selectable.
The Allow instance value to be configured check box is selected by default for function block parameters with the Common Configuration filter. You can make other parameters editable in the instance by selecting the Allow instance value to be configured check box in the class.
Selected and grayed out — The parameter value is configurable in a module instance. The parameters are in this category include:
Not selected and grayed out — The parameter value is not configurable in a module instance. The parameters in this category include:
User-defined dynamic reference parameters are configurable in the class or the instance.
Block scan rates are not editable in module instances.
There are two ways to configure parameters in module classes and module instances: