Hello people,
nodeid from OPC UA Server have this number for example the 123 below:
ns=2;s=123:cluster.tagname.field
Looks like that this number reset on new session, and is increased on tag browsing.
And this makes the purpose of use OPC UA Server to share data with another system broken, since the addresses changes on each connection.
Firstly, you need to disable browsing properties and extensions for speeding up browse operation. It is not recommended to use the equipment format for requesting SCADA runtime data.
As for the OPC UA node ID, Plant SCADA OPC UA server uses Name Space = 3 with the string type of identifiers to compose a Node ID. The Node ID syntax should be ns=3;s=a:<Cluster Name>.<Tag Name> where an identifier is global when a=0, and it could also have a>0 when being retrieved from an OPC UA browse session. The hierarchy of browsed tags is based on the equipment structure defined in a SCADA project. The “Browse Position Index” (a>0) will be included in Node ID when if tags are imported by an OPC UA browse session.
The “Browse Position Index” should be persisted unless the structure of the tag name space is altered on the SCADA side. In this case, a resynch would be required. For example, a new piece of equipment is added in a SCADA project and referenced in variable tags. Any Node ID below the newly added equipment in hierarchy will change their "Browse Position Index" in a new OPC UA browse session.
It is possible to break the runtime data when the Node ID with a new "browse position index" is used for request. In general, OPC UA clients should ignore the "browse position index" part of Node IDs when creating monitored items for any runtime data request.
Alternatively, you could build Node IDs with the following syntax without a browse session.
ns=3;s=<Cluster Name>.<Tag Name>
Firstly, you need to disable browsing properties and extensions for speeding up browse operation. It is not recommended to use the equipment format for requesting SCADA runtime data.
As for the OPC UA node ID, Plant SCADA OPC UA server uses Name Space = 3 with the string type of identifiers to compose a Node ID. The Node ID syntax should be ns=3;s=a:<Cluster Name>.<Tag Name> where an identifier is global when a=0, and it could also have a>0 when being retrieved from an OPC UA browse session. The hierarchy of browsed tags is based on the equipment structure defined in a SCADA project. The “Browse Position Index” (a>0) will be included in Node ID when if tags are imported by an OPC UA browse session.
The “Browse Position Index” should be persisted unless the structure of the tag name space is altered on the SCADA side. In this case, a resynch would be required. For example, a new piece of equipment is added in a SCADA project and referenced in variable tags. Any Node ID below the newly added equipment in hierarchy will change their "Browse Position Index" in a new OPC UA browse session.
It is possible to break the runtime data when the Node ID with a new "browse position index" is used for request. In general, OPC UA clients should ignore the "browse position index" part of Node IDs when creating monitored items for any runtime data request.
Alternatively, you could build Node IDs with the following syntax without a browse session.
ns=3;s=<Cluster Name>.<Tag Name>
