OPC UA Historical Access|OPC UA Standard|Forum|OPC Foundation

Hello everyone,

I’m implementing a component for historical access in our application. If a node which is monitored goes offline this status change should be tracked. If the node is online again, the data from the offline interval should be fetched and processed. Some questions arise:

1) How to get the online/offline status change of a node. Is this the StatusCode assigned to a value as defined in 7.7.5, Part 4: Services? Or do I have to listen to a special event or something else?

If a VariableNode is historizing and has historical data stated by its UserAccessLevel, my approach is to call Session::HistoryReadRaw. 

2) Will I get different data by this, e.g the node is offline and sends -1, bad for a time interval. If I call HistoryReadRaw for this interval, will I get good values, e.g 4, good; 5,good; 2, good; …  ? Or do I have to do something else, e.g call another node which is a pure historical node storing historical data for the original observed node?

Thanks for any advice

Regards
Simon