Build an OPC UA bridge in Python: https://h3xagn.com

opcua-bridge.py

# Import libraries
import asyncio
import json

# Import OPC UA library
from asyncua import Client, Node


# Create handler for subscriptions
class SubscriptionHandler:
    def __init__(self, destination_client):
        self.destination_client = destination_client

    async def datachange_notification(self, node: Node, val, data):
        """Once a new value is received from the source, lookup the destination node id and write it to the destination server"""

        if data.monitored_item.Value.Value.Value is not None:
            # Get the source value
            source_value = data.monitored_item.Value.Value.Value
            # Get the source node id
            source_nodeid = f"ns=3;s={node.nodeid.Identifier}"
            # Lookup destination node id
            destination_node_id = f'ns=2;s={tags[source_nodeid]["tagName"]}'
            # Get the node in the destination server
            destination_node = self.destination_client.get_node(destination_node_id)
            # Write the value to the destination
            await destination_node.write_value(source_value)


# Main function
async def read_and_write_value(source_server_url, source_node_id, destination_server_url):
    """Connects to both source and destination servers and subscribes to all the source node ids provided in tags.json"""

    # Connect to source OPC UA server
    source_client = Client(url=source_server_url)
    await source_client.connect()

    # Connect to destination OPC UA server
    destination_client = Client(url=destination_server_url)
    await destination_client.connect()

    # Create a handler for the subscription
    handler = SubscriptionHandler(destination_client)

    # Create an instance of the custom subscription class
    subscription = await source_client.create_subscription(5000, handler)

    # Add the source node ids to the subscription
    for source_node_id in source_node_ids:
        source_node = source_client.get_node(source_node_id)
        await subscription.subscribe_data_change(source_node)

    try:
        # Run the event loop
        while True:
            await asyncio.sleep(5)
    finally:
        # Disconnect open subscriptions
        await source_client.disconnect()
        await destination_client.disconnect()


# Set up the source OPC UA server
source_server_url = "opc.tcp://192.168.0.1:4840/"

# Set up the destination OPC UA server
destination_server_url = "opc.tcp://10.10.10.1:4940/HIST001"

# Read node ids from the JSON file
with open(f"tags.json", "r") as json_file:
    tags = json.load(json_file)

# Add source node ids to a list
source_node_ids = []

for source_node_id in tags:
    source_node_ids.append(source_node_id)

# Run the main function
asyncio.run(read_and_write_value(source_server_url, source_node_ids, destination_server_url))