I have read the example of OPCUA----Ignition-ModuleSDK-7.2.8\example\WeatherModule_Gateway,the example show how to build nodes,and get node value from others sourse(In this example :Weather service from a web service),so it can read the node value,but how can I write a value to a node ,in other words: change the node’s value,and in response to change the value from others sourse,thank you very much.
The way the weather driver works is that there’s a lot of machinery going on in the background as a result of extending from NodeMapDriver that leads to values being asked of DataNode - not the other way around.
But for any driver what ultimately happens when a subscription is made is that you get a SubscriptionItem for each address. SubscriptionItem extends ReadItem, which has a setValue(DataValue) call on it. This call is how the driver communicates value changes back to the server.
These interfaces (SubscriptionItem, ReadItem) are documented in the javadocs as well.
Thank your very much.
Can you give me more detailed inforamtion about it,A framework of code about how to read and write a value to a node will be appreciated.