Change trigger specifies what changes the tag should notify all “interested” consumers about (OPC UA variable, time series, etc.). The following values are available:
- StatusValue ensures the best performance, because in this mode the notifications are only sent after a change of status (for example, when the connection is lost) or value.
- StatusValueTimestamp is the most resource-intensive notification mode. In this mode, the tag will signal its change with the frequency specified in the Update Rate, regardless of whether the status or value of the tag has changed or not.
Change trigger affects the amount of data saved in the store if the tag is associated to a time series, as well as the filtering mode for OPC UA subscription.