Browse an OPC UA address space in Python

The code

import asyncio
from asyncua import Client, ua

async def walk(node, depth=0, limit=2):
    for child in await node.get_children():
        bn = await child.read_browse_name()
        nc = await child.read_node_class()
        print("  " * depth + f"{bn.NamespaceIndex}:{bn.Name}  [{nc.name}]  {child.nodeid.to_string()}")
        if depth < limit:
            await walk(child, depth + 1, limit)

async def main():
    async with Client(url="opc.tcp://opcua.umati.app:4840") as client:
        await walk(client.nodes.objects)

asyncio.run(main())

What it prints

0:Server  [Object]  i=85
  0:ServerStatus  [Variable]  i=2256
3:Machines  [Object]  ns=3;i=1001
  4:MachineTool_1  [Object]  ns=4;i=5001
    2:Identification  [Object]  ns=2;i=6001
    4:Production  [Object]  ns=4;i=6100

Notes

• `client.nodes.objects` is the Objects folder. There is also `client.nodes.root`, `types` and `server`.
• Check `read_type_definition()` on anything that looks like a machine. If it returns MachineToolType or a PackML type, your integration is a mapping job rather than a tag hunt.
• Do not browse recursively on every startup in production. Browse once, store namespace URI plus identifier, and use browse paths afterwards.
• The `uals` CLI does this without any code: `uals -u opc.tcp://opcua.umati.app:4840 -l 3`.

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.