Error handling for OPC UA Server nodes with "Null" data type

Using a combination of Honeywell Experion OPC UA and the Aveva OPC UA Adapter, we have observed that when an instrument physically fails in the field or goes offline / stops sending communication to the Experion server, it may appear in the Honeywell OPC UA Server with no value and a data type of "Null".

Using UAExpert, Statuscode for the node IDs may appear as BadUnexpectedError or BadWaitingForInitialData

This behavior will freeze the value in PI Vision with the last good value and flat line until the instrument is back online. Then the data is interpolated.

It is a misleading behavior that could lead the user to believe there is nothing wrong with the instrument if the value still appears. Rather than showing last good value, it should write a "BAD" or "ERROR" value to the tag in the Data Archive to indicate there is a problem.

The OMF Egress logs reports the following error when these conditions with Null Datatype occurs:

"The default data type of <streamId> could not be determined. Value is ignored."