Tutorials¶

Intro Example in a Python Shell¶

This quick example assumes an OPC UA server is already running on localhost:4840. It shows the minimal flow from connect to read/write and disconnect using the high-level Client.

1. Import the required objects¶

The Client class is the main entry point for a high-level OPC UA workflow. For namespace-aware references, o6.ns provides convenient helpers and prebuilt namespace definitions.

import o6

2. Create a client and connect¶

Initialize the client with the server endpoint and connect. This establishes the OPC UA session and prepares the client for subsequent requests.

client = o6.Client("opc.tcp://localhost:4840")
client.connect()

3. Browsing namespaces with o6.ns¶

The o6.ns module lets you address OPC UA nodes using namespace-aware helpers and built-in identifiers. This keeps your code clearer and reduces the chance of mistakes when working with standard names or custom namespaces.

current_time_nodeid = o6.ns.ns0.objects.Root.Objects.Server.ServerStatus.CurrentTime()

OPC UA companion specs are included as well

o6.ns.di.objects.DeviceSet()

o6.NodeId('ns=1;i=5001')

4. Read and write values¶

Use read and write to interact with NodeIds. If you resolve NodeIds through o6.ns, the API stays consistent and easier to maintain.

client.read(current_time_nodeid)

o6.DateTime(2026-04-20T10:15:00.0000000Z)

Write variables on the server

client.write("ns=1;s=MyVariable", 20.0)

Or browse, read and write nodes directly

client.read(current_time_nodeid)

o6.DateTime(2026-04-20T10:15:00.0000000Z)

c.root.Objects.Server.ServerStatus.CurrentTime(attr=o6.AttributeId.NODECLASS)

<NodeClass.Variable: 2>

c.root.Objects.MyVariable(123.4)

5. Disconnect the client¶

Always disconnect the client when you are done. This cleanly releases the session and any resources held by the connection. Dropping the Client object without calling disconnect() can cause side effects because cleanup and resource release will happen later in an unspecified order during garbage collection.

client.disconnect()