Browse an OPC UA address space in C#

The code

var browser = new Browser(session)
{
    BrowseDirection = BrowseDirection.Forward,
    ReferenceTypeId = ReferenceTypeIds.HierarchicalReferences,
    IncludeSubtypes = true,
    NodeClassMask   = (int)(NodeClass.Object | NodeClass.Variable),
    ResultMask      = (uint)BrowseResultMask.All,
};

ReferenceDescriptionCollection refs = browser.Browse(ObjectIds.ObjectsFolder);

foreach (var r in refs)
{
    Console.WriteLine($"{r.BrowseName,-24} {r.NodeClass,-10} {r.NodeId}");
    Console.WriteLine($"    type: {r.TypeDefinition}");
}

What it prints

3:Machines                Object     ns=3;i=1001
    type: ns=0;i=61
2:DeviceSet                Object     ns=2;i=5001
    type: ns=0;i=61
0:Server                   Object     i=85
    type: i=2004

Notes

• The Browser helper handles continuation points for you, which is why it is worth using over raw Browse calls.
• Filter in the request with NodeClassMask and ReferenceTypeId. Fetching everything and filtering in LINQ costs a round trip and the server's continuation points.
• Check TypeDefinition against MachineToolType or a PackML type early. It changes the whole shape of the integration.
• Once you know the model, switch to TranslateBrowsePathsToNodeIds. Browsing on every startup does not scale.

What breaks first

Last verified 7 September 2026 against OPC UA 1.05.07. OPC UA Connect is an educational resource and is not affiliated with the OPC Foundation.