Gets/Sets the active state of the Tag class instance
When set to TRUE, ReadTag, WriteTag, GroupRead and GroupWrite will perform an operation on the tag.
When set to FALSE, Controller.ReadTag, Controller.WriteTag, Controller.GroupRead and Controller.GroupWrite will ignore the tag during operation.
When FALSE, the QualityCode and QualityString will equal QUAL_UNCERTAIN and QUAL_STRING_UNCERTAIN respectively. Now will operate regardless of the Active state.
Active is useful to suspend specific tag read/write operations within TagGroup classes.