Child Tags

Child tags are specialized tags that are essentially used as a grouping mechanism for like objects, and as a rapid means of launching multiple objects. They are typically used for something self-contained, such as a generator or lift station which may include a large number of I/O tags.  In such a configuration, the generator or lift station is referred to as the "parent", while the I/O are referred to as the "child tags".

Custom script code must be used for child tags, and their parameters do not exist within the tag properties database as do the parameters of the standard tag types. This structure saves you from having to define lots of tags in Points.mdb.

Despite the fact that the properties of child tags are not stored in the tag properties database, they do appear listed in the Tag Browser. However, because the properties of child tags are not stored in the tag properties database, the Tag Browser's Properties button will be disabled when a child tag is selected in the Tag Browser. You cannot edit the properties of a child tag using the Tag Browser; you must use code. It follows that records are not written to the tag properties database when a child tag is created.

The section that follows provides sample code for a parent module and its child tags. A key function to be aware of is StartTag. This function is used to create tags by starting new instances of the tag type specified in the parameter list. 

This example code is commented for your convenience. Some key points to consider when using child tags are listed in Optimizations and Considerations When Using Child Tags.