Pure Python OPC-UA / IEC 62541 Client and Server Python 2, 3 and pypy . http://freeopcua.github.io/, https://github.com/FreeOpcUa/python-opcua

OPC-UA implementation is quasi complete and has been tested against many different applications. API 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. It is easy to mix high level objects and low level UA calls in one application.

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 only dependency is cryptography. If using python 2.7 or pypy < 3 you need to install enum34, trollius(asyncio), and futures(concurrent.futures), with pip for example.

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/

A simple GUI client is available: https://github.com/FreeOpcUa/opcua-client-gui

Examples: https://github.com/FreeOpcUa/python-opcua/tree/master/examples

A set of command line tools also available: https://github.com/FreeOpcUa/python-opcua/tree/master/tools

• uadiscover (find_servers, get_endpoints and find_servers_on_network calls)
• uals (list children of a node)
• uahistoryread
• uaread (read attribute of a node)
• uawrite (write attribute of a node)
• uasubscribe (subscribe to a node and print datachange events)
• uaclient (connect to server and start python shell)

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
• history read
• login with certificate
• communication encryption

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

Client: what is not implemented yet

• removing nodes
• adding some missing modify methods

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)
• encryption
• certificate handling

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

Server: what is not implemented

• complete securty model with users
• removing nodes
• adding some missing modify methods

Example minimal 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 minimal server code:

    from opcua import ua, Server, ObjectIds

    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()
    ...

or starting a server using command line and supporting encryption:

tools/uaserver --populate --certificate cert.pem --private_key pk.pem

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