Pure Python OPC-UA / IEC 62541 Client and Server
http://freeopcua.github.io/, https://github.com/FreeOpcUa/python-opcua

API is similar to the python bindings of freeopcua c++ client and servers. It offers both a low level interface to send and receive all UA defined structures and high level classes allowing to write a server or a client in a few lines.

Most code is autogenerated from xml specification using same code as the one that is used for freeopcua C++ client and server, thus adding missing functionnality to client and server shoud be trivial.

Using Python > 3.4 the server and client do not require any third party libraries. If using python 2.7 or pypy < 3 you need to install enum34, trollius(asyncio), and futures(concurrent.futures), with pip for example. Server and client can be run with pypy.

coveryage.py reports a test coverage of over 90% of code, most of non-tested code is autogenerate code that is not used yet.

Some documentation is available at http://python-opcua.readthedocs.org/en/latest/

Client: what works:

• connection to server, opening channel, session
• browsing and reading attributes value
• gettings nodes by path and nodeids
• creating subscriptions
• subscribing to items for data change
• subscribing to events
• adding nodes
• method call
• user and password

Tested servers: freeopcua C++, freeopcua Python, prosys

Client: what is not implemented yet

• removing nodes
• adding missing modify methods
• certificate handling

Server: what works:

• creating channel and sessions
• read/set attributes and browse
• gettings nodes by path and nodeids
• autogenerate addres space from spec
• adding nodes to address space
• datachange events
• events
• methods
• basic user implementation (one existing user called admin, which can be disabled, all others are read only)

Tested clients: freeopcua C++, freeopcua Python, uaexpert, prosys, quickopc

Server: what is not implemented

• security (users, certificates, etc)
• removing nodes
• adding missing modify methods

Example client code:

from opcua import ua, Client

class SubHandler(object):
    def data_change(self, handle, node, val, attr):
        print("Python: New data change event", handle, node, val, attr)

    def event(self, handle, event):
        print("Python: New event", handle, event)

if __name__ == "__main__": 
    client = Client("opc.tcp://localhost:4841/freeopcua/server/")
    client.connect()
    
    root = client.get_root_node()

    #getting a variable by path and setting its value attribute
    myvar = root.get_child(["0:Objects", "2:NewObject", "2:MyVariable"])
    var.set_value(ua.Variant([23], ua.VariantType.Int64))
    
    #subscribing to data change event to our variable
    handler = SubHandler()
    sub = client.create_subscription(500, handler)
    sub.subscribe_data_change(myvar)
    
    time.sleep(100)

    client.disconnect()

Example server code:

    from opcua import ua, Server

    server = Server()
    
    server.set_endpoint("opc.tcp://localhost:4841/freeopcua/server/")
    server.set_server_name("FreeOpcUa Example Server")
    uri = "http://examples.freeopcua.github.io"
    idx = server.register_namespace(uri)
    objects = server.get_objects_node()
    myfolder = objects.add_folder(idx, "myfolder")
    myvar = myfolder.add_variable(idx, "myvar", 6.7)

    # creating an event object
    myevent = server.get_event_object(ObjectIds.BaseEventType)
    myevent.Message.Text = "This is my event"
    myevent.Severity = 300
    
    server.start()
    myevent.trigger()
    ...

Development

Code follows PEP8 apart for line lengths and autogenerate class and enums that keep camel case from XML definition.

Running tests:

python tests.py

Coverage

coverage run tests.py
coverage html
firefox htmlcov/index.html