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import asyncio |
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import logging |
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from asyncua import Client |
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logging.basicConfig(level=logging.INFO) |
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_logger = logging.getLogger('asyncua') |
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10
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class SubHandler(object): |
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""" |
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Subscription Handler. To receive events from server for a subscription |
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data_change and event methods are called directly from receiving thread. |
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Do not do expensive, slow or network operation there. Create another |
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thread if you need to do such a thing |
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""" |
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def datachange_notification(self, node, val, data): |
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print("New data change event", node, val) |
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def event_notification(self, event): |
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print("New event", event) |
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async def main(): |
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url = "opc.tcp://localhost:4840/freeopcua/server/" |
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async with Client(url=url) as client: |
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root = client.get_root_node() |
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_logger.info("Root node is: %r", root) |
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objects = client.get_objects_node() |
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_logger.info("Objects node is: %r", objects) |
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# Node objects have methods to read and write node attributes as well as browse or populate address space |
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_logger.info("Children of root are: %r", await root.get_children()) |
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uri = "http://examples.freeopcua.github.io" |
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idx = await client.get_namespace_index(uri) |
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_logger.info("index of our namespace is %s", idx) |
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# get a specific node knowing its node id |
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#var = client.get_node(ua.NodeId(1002, 2)) |
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#var = client.get_node("ns=3;i=2002") |
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#print(var) |
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#var.write_data_value() # get value of node as a DataValue object |
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#var.read_value() # get value of node as a python builtin |
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#var.write_value(ua.Variant([23], ua.VariantType.Int64)) #set node value using explicit data type |
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#var.write_value(3.9) # set node value using implicit data type |
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# Now getting a variable node using its browse path |
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myvar = await root.get_child(["0:Objects", "2:MyObject", "2:MyVariable"]) |
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obj = await root.get_child(["0:Objects", "2:MyObject"]) |
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_logger.info("myvar is: %r", myvar) |
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# subscribing to a variable node |
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handler = SubHandler() |
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sub = await client.create_subscription(500, handler) |
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handle = await sub.subscribe_data_change(myvar) |
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await asyncio.sleep(0.1) |
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60
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# we can also subscribe to events from server |
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await sub.subscribe_events() |
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# await sub.unsubscribe(handle) |
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# await sub.delete() |
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# calling a method on server |
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res = await obj.call_method("2:multiply", 3, "klk") |
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_logger.info("method result is: %r", res) |
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if __name__ == "__main__": |
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asyncio.run(main()) |
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FreeOpcUa /
opcua-asyncio
