Using CitectSCADA > Defining and Drawing Graphics Pages > Understanding Object Types > ActiveX Object Properties - Appearance (Tag Association)

ActiveX Object Properties - Appearance (Tag Association)

ActiveX objects have the following appearance properties:


The "properties" of an ActiveX object relate to the elements that define the object's functionality and appearance. The available properties for a selected ActiveX object are listed here, as defined by the object's creator.

The check box to the left of each item on the list indicates whether or not a tag has been associated with the Property. If the box is checked, it means an association has already been defined for the property. If you want to clear this tag association, simply uncheck the box, or clear the tag from the "Associate property with tag. . ." field.

Associate property with tag

You can create an association between an ActiveX object property and a variable tag so that changing values in one are reflected in the other. To create an association, you need to first choose a property from the property list. The label Associate property with tag will change to display the property name.

Select the variable tag you would like to associate with a property by clicking on the Wizard button and choosing from the list of available tags. Alternatively, the tag name can be typed in to the Associate property with tag field.

Note: You can only use variable tag names in this field. Functions, expressions and constants are not supported when defining ActiveX property tag associations.

You can only associate a property with a variable tag if the tag type is compatible with the property. To display a list of compatible tag types, select the property, and click List Property Types. A list of compatible data types will display, or a message will inform you that there are no compatible types.

If there are no types compatible with the property, the Associate Property with tag and Update association on fields will be disabled.

If you specify a tag which might be inappropriate for the selected ActiveX property, the Type Evaluation dialog will display an alert. This might happen if:


If an object property is "bindable", it means it can automatically send notification of value changes to CitectSCADA, and acknowledge any value changes from an associated tag. This means both the property and an associated tag will automatically update whenever the value for either changes.

If a property is not bindable, the property/tag association can only be synchronized according to the event selected in the Update association on Event field.

Be aware that if an object property is bindable, the Update association on Event field will be automatically set to <Property change notification> by default. You can change this setting if you want the tag association to be updated by a more specific event.

For properties that are not bindable, you can mimic the behavior of <property change notification> by selecting After update for the Update association on Event field.

Property status

This indicates the read/write status of the selected property. With ActiveX objects, some properties are read-only, whereas others accept value changes. If a property is marked "read only", it indicates that its value is fixed and can only be read by CitectSCADA. If its status is read/write, can modify the property during runtime via a tag association.

Update association on Event:

This defines when you want a value update to occur for the selected property and its associated tag. Use the menu to the right of the Event field to view events that can be used to trigger a tag association update.

The available events that can be used with a particular property are predefined by an object's creator. They typically include user interaction events (for example, mouse clicks), time events (such as a new day or new month), or value changes (such as "after update").

Property documentation

Most ActiveX objects have documentation describing the object's controls and functionality. Some have a separate Help file included, others, simple text prompts to explain each property. This depends on what an object's creator has included.

The Property documentation field displays Help information for a selected property, or give instructions to obtain the Help necessary for a selected property. Usually the following message will appear:

"Click the '?' button to the right to display the Help topic for this property"

The Help button displays the ActiveX object Help file (if included), usually with the topic displayed that relates to the selected property. It will also provide information about settings provided on additional tabs the ActiveX object might call up on the properties dialog.

Clear Property

The Clear Property button clears the tag associations for each of the ActiveX object properties. To clear a tag association for a particular object property, clear the check box to the left of the property.

If you accidentally click Clear Property, you can restore your tag associations by clicking Cancel and reopening the ActiveX properties dialog.