Subscribing to Codesys standard OPC UA events

[mozesa]

Hello,

First of all thanks for your effort putting into this precious project.

I am using Codesys runtime which provides OPC UA Server interface.
It works fine with opcua-asyncio, I have been using subscribe_data_change in production for almost half a year without any issue.

Now, I would like to do the same for events with subscribe_events.
I created the wanted OPC UA events based on this guide and I can see those ones using UaExpert but cannot using the below snippet.

import asyncio

from asyncua import Client


class SubscriptionHandler:
    def event_notification(self, event):
        print(f"{event=}")


async def main():
    client = Client(url="opc.tcp://127.0.0.1:4840/")
    async with client:
        obj = await client.nodes.root.get_child(
            ["0:Objects", "2:DeviceSet", "4:CODESYS Control Win V3 x64", "4:Application"]
        )
        events = await client.nodes.root.get_child(
            ["0:Types", "0:EventTypes", "0:BaseEventType", "0:ConditionType"]
        )

        # We create a Client Subscription.
        handler = SubscriptionHandler()
        sub = await client.create_subscription(500, handler)
        handle = await sub.subscribe_events(obj, events)
        await asyncio.sleep(60)
        await sub.unsubscribe(handle)
        await sub.delete()


if __name__ == "__main__":
    asyncio.run(main())

On the below image I marked red the events I would like to subscribe to.

What I am doing wrong?

I would appreciate your help.

Thanks in advance.

[AndreasHeine]

opcua-asyncio/asyncua/common/subscription.py

Line 189 in 51fb682

async def subscribe_events(self,

is "4:Application" really the emitting node or is it "Server" ?

[mozesa]

import asyncio

from asyncua import Client


class SubscriptionHandler:
    def event_notification(self, event):
        print(f"{event=}")


async def main():
    client = Client(url="opc.tcp://127.0.0.1:4840")
    async with client:
        obj = await client.nodes.root.get_child(
            [
                "0:Objects",
                "0:Server",
                # "4:CODESYS Control Win V3 x64",
                # "4:Application",
            ]
        )
        events = await client.nodes.root.get_child(
            [
                "0:Types",
                "0:EventTypes",
                "0:BaseEventType",
                "0:ConditionType",
            ]
        )

        # We create a Client Subscription.
        handler = SubscriptionHandler()
        sub = await client.create_subscription(500, handler)
        handle = await sub.subscribe_events(obj, events)
        await asyncio.sleep(60)
        await sub.unsubscribe(handle)
        await sub.delete()


if __name__ == "__main__":
    asyncio.run(main())

I altered the code, but no success. I don't get any events.
Strange b/c I can see those events in UaExpert (Event View) using Application as object.
It can be that I am wrong (as so far I used only subscribe_data_change).

[AndreasHeine]

have you tried the codesys device instead of server? the emitting node must have a reference which shows that it emitts events

[mozesa]

No, it doesn't report anything at all. 😞

import asyncio

from asyncua import Client


class SubscriptionHandler:
    def event_notification(self, event):
        print(f"{event=}")


async def main():
    client = Client(url="opc.tcp://127.0.0.1:4840")
    async with client:
        obj = await client.nodes.root.get_child(
            [
                "0:Objects",
                "2:DeviceSet",
                "4:CODESYS Control Win V3 x64",
                # "4:Application",
            ]
        )
        events = await client.nodes.root.get_child(
            [
                "0:Types",
                "0:EventTypes",
                "0:BaseEventType",
                "0:ConditionType",
            ]
        )

        # We create a Client Subscription.
        handler = SubscriptionHandler()
        sub = await client.create_subscription(500, handler)
        handle = await sub.subscribe_events(obj, events)
        print("*** Sleep ***")
        await asyncio.sleep(60)
        await sub.unsubscribe(handle)
        await sub.delete()


if __name__ == "__main__":
    asyncio.run(main())

[AndreasHeine]

please post the references of "server", "4:CODESYS Control Win V3 x64" and "4:Application"

ther must be a reference which says "GeneratesEvents" or "HasCondition"!?

[mozesa]

I really appreciate your help!

As I have mentioned, I get the events using UaExpert.
I enclosed some pictures about that too.

[AndreasHeine]

there it is the "HasNotifier" reference 😉 could you try to subscribe the baseevent on server? this should show all events which are emitted!

[AndreasHeine]

https://reference.opcfoundation.org/v104/Core/docs/Part3/7.18/

[mozesa]

It doesn't show anything. 😞

The events are visible only in UaExpert.

import asyncio

from asyncua import Client


class SubscriptionHandler:
    def event_notification(self, event):
        print(f"{event=}")


async def main():
    client = Client(url="opc.tcp://127.0.0.1:4840")
    async with client:
        obj = await client.nodes.root.get_child(
            [
                "0:Objects",
                "0:Server",
                # "4:CODESYS Control Win V3 x64",
                # "4:Application",
            ]
        )
        events = await client.nodes.root.get_child(
            [
                "0:Types",
                "0:EventTypes",
                "0:BaseEventType",
                # "0:ConditionType",
            ]
        )

        # We create a Client Subscription.
        handler = SubscriptionHandler()
        sub = await client.create_subscription(50, handler)
        handle = await sub.subscribe_events(obj, events)
        print("*** Sleep ***")
        await asyncio.sleep(60)
        await sub.unsubscribe(handle)
        await sub.delete()


if __name__ == "__main__":
    asyncio.run(main())

[mozesa]

I creating the subscription with the following parameters with UaExpert.

Creating new subscription:

• ClientHandle=2
• PublishingEnable=1
• LifeTimeCount=2400
• MaxKeepAliveCount=10
• Priority=0
• PublishingInterval=500

I can see from the server information (CurrentSubscriptionCount) that the subscription is successful.

I enclosed the logs, I am trying to find the differences.
UaExpert_log.txt
asyncua_log.txt

[mozesa]

Using QuickOPC I can subscribe to events.

def subscribe_to_events():
    endpoint_descriptor = UAEndpointDescriptor("opc.tcp://L042IEAMO2:4840")

    # Instantiate the client object and hook events
    client = EasyUAClient()
    client.EventNotification += print

    # client.SubscribeEvent(endpoint_descriptor, AddressSpace.Standard.UAObjectIds.Server, 1000)
    IEasyUAClientExtension.SubscribeEvent(
        client,
        endpoint_descriptor,
        UANodeDescriptor(AddressSpace.Standard.UAObjectIds.Server),
        1_000,
    )
    Threading.Thread.Sleep(30 * 1000)

{Isolated=False} [] Success
{Isolated=False} [] Success; Refresh; RefreshInitiated
{Isolated=False} [] Success; Refresh; RefreshComplete
{Isolated=False} [] Success; (10 field results) [Application] 1000! "TRUE" @19/05/2021 08:39:59
{Isolated=False} [] Success; (10 field results) [Application] 1000! "TRUE" @19/05/2021 08:39:59
{Isolated=False} [] Success; (10 field results) [Application] 1000! "TRUE" @19/05/2021 08:39:59
{Isolated=False} [] Success; (10 field results) [Application] 1000! "TRUE" @19/05/2021 08:40:04
{Isolated=False} [] Success; (10 field results) [Application] 1000! "TRUE" @19/05/2021 08:40:04
{Isolated=False} [] Success; (10 field results) [Application] 1000! "TRUE" @19/05/2021 08:40:04

So what is the difference between opcua-asyncio vs UaExpert / QuickOPC.

[mozesa]

class SimpleAttributeOperand(FrozenClass):

    def __init__(self):
        self.TypeDefinitionId = NodeId(2041)  # Using this NodeId it works, but why?!

Previously it was TypeDefinitionId:i=0.

Is it a bug?

[swamper123]

2041 is the BaseEventType, which should always work.

[mozesa]

async def main():
    client = Client(url="opc.tcp://127.0.0.1:4840/")
    async with client:
        obj = await client.nodes.root.get_child(
            [
                "0:Objects",
                "2:DeviceSet",
                "4:CODESYS Control Win V3 x64",
                "4:Application",
            ]
        )
        events = await client.nodes.root.get_child(
            [
                "0:Types",
                "0:EventTypes",
                "0:BaseEventType",
                "0:ConditionType",
            ]
        )

        # We create a Client Subscription.
        handler = SubscriptionHandler()

        params = CreateSubscriptionParameters()
        params.RequestedPublishingInterval = 500
        params.RequestedLifetimeCount = 2400
        params.RequestedMaxKeepAliveCount = 10
        params.MaxNotificationsPerPublish = 10_000
        params.PublishingEnabled = 1
        params.Priority = 0

        sub = await client.create_subscription(params, handler)
        handle = await sub.subscribe_events(obj, events, queuesize=50)
        print("*** Sleep ***")
        await asyncio.sleep(60)
        await sub.unsubscribe(handle)
        await sub.delete()

events == 2782

I don't get any events.

But when I manually overwrite it in /asyncua/ua/uaprotocol_auto.py with self.TypeDefinitionId = NodeId(2782), I finally get all the events.

Do I miss something?

Strange. The line which is responsible for TypeDefinitionId is commented out.

async def where_clause_from_evtype(evtypes):
    cf = ua.ContentFilter()
    el = ua.ContentFilterElement()
    # operands can be ElementOperand, LiteralOperand, AttributeOperand, SimpleAttribute
    # Create a clause where the generate event type property EventType
    # must be a subtype of events in evtypes argument

    # the first operand is the attribute event type
    op = ua.SimpleAttributeOperand()
    # op.TypeDefinitionId = evtype.nodeid

It never gets the set to the proper nodeid.

[swamper123]

2782 is the index for the ConditionType.
https://raw.githubusercontent.com/FreeOpcUa/opcua-asyncio/master/asyncua/ua/object_ids.py

Just a guess from my side: Could you subscribe to a single EventType? Like just the BaseEventType?
And then try to create multiple single handles for each event Type?

[mozesa]

The problem that SimpleAttributeOperand is a FrozenClass subtype so it never gets updated later, this is the reason for it has i=0 id.
Plus it is commented out too 😄

[mozesa]

I am at the latest master commit rev = "51fb682".

The problem that evfilter TypeDefinitionId is wrong, I mean the Identifier == 0.

Or am I wrong?

[mozesa]

Explicitly giving Node's Identifier, works.
I know it is a dirty workaround.

Btw, does this function work properly or it is a bug?

[AndreasHeine]

i am on 0.9.14 and i tested it against the prosys simserver:

[AndreasHeine]

i would guess 0 is just a default which never gots overwritten in the code... but i need some time to look deeper unfortunatly i have no codesys stuff to test against...

[mozesa]

You can download Codesys developer.

After installing it, it will also install a soft plc (Runtime Win) and a gateway, all in all, you can freely use it to test against freeopcua (it is a full version for 2 hours).

Anyway I can help you as much as you would like. I really want to release the production version of my program without that nightmarish monkey patch.

[AndreasHeine]

can you provide a test project?

[mozesa]

Here you are the project.

If you have any questions, let me know.

Thanks for your help.

[ghost]

i would guess 0 is just a default which never gots overwritten in the code... but i need some time to look deeper unfortunatly i have no codesys stuff to test against...

That's correct,
in our fork of this library asyncua/common/events.py I've set the TypeDefinitionId with the NodeId of evtypes, which was subscribed to and the subscription is working for the Euromap77/83 server of our machine.
But it's the first try, so it can potentially cause many bugs for other servers or subscripions of other events.

[mozesa]

@AndreasHeine I really appreciate your help!

I recreated the asyncua part based on your snippet, but unfortunately it did not help.

import asyncio

from asyncua import Client


class Handler:
    def event_notification(self, event) -> None:
        print(f"{event=}")


async def async_main():
    client = Client("opc.tcp://L042IEAMO2:4840")
    async with client:
        ev_src = client.get_node("ns=4;s=|var|CODESYS Control Win V3 x64.Application")
        ev_type_node = client.get_node("ns=0;i=2782")
        handler = Handler()
        sub = await client.create_subscription(500, handler)
        await sub.subscribe_events(ev_src, ev_type_node)
        await asyncio.sleep(60)


if __name__ == "__main__":
    asyncio.run(async_main())

I could narrow this issue down to the following facts (please see the screenshot).

• (1) ev_src node.
• (1.1) ev_type_node node.
• (2) The SelectClauses based on UaExpert's log.
  You can clearly see that each element has TypeDefinitionId with value NS0|Numeric|2041 .
• (3) The same SelectClauses resulted by asyncua.
  You can see that all the TypeDefinitionIds value is i=0.

I don't know why but Codesys OPC UA server does require the proper TypeDefinitionId set.
I have done some tests using QuickOPC which also works fine with Codesys OPC UA server.

In the documentation it is written that

typeDefinitionId is NodeId of a TypeDefinitionNode.

which implies me that it really should be i=2782, I thought.

After monkey patching SimpleAttributeOperand class

Asyncua works fine.
Notice that now TypeDefinitionId is 2782.

Thanks for your support.

[AndreasHeine]

Rrevised values: thats normal you requested parameters which the server is not capable of and the server send you new parameters to use!

Ack Alarms: how do you ack them? Codesnipped?

[Saleem344]

Rrevised values: thats normal you requested parameters which the server is not capable of and the server send you new parameters to use!

Ack Alarms: how do you ack them? Codesnipped?

Hi @AndreasHeine
Thanks for your response.
I would like to know how to read the events from python client because I can see it in UaExpert.

ack I'm able to do it from UaExpert not from python.

Thanks.

[AndreasHeine]

Rrevised values: thats normal you requested parameters which the server is not capable of and the server send you new parameters to use!

Ack Alarms: how do you ack them? Codesnipped?

Hi @AndreasHeine
Thanks for your response.
I would like to know how to read the events from python client because I can see it in UaExpert.

ack I'm able to do it from UaExpert not from python.

Thanks.

https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples/client_to_uanet_alarm_conditions.py

[Saleem344]

Rrevised values: thats normal you requested parameters which the server is not capable of and the server send you new parameters to use!
Ack Alarms: how do you ack them? Codesnipped?

Hi @AndreasHeine
Thanks for your response.
I would like to know how to read the events from python client because I can see it in UaExpert.
ack I'm able to do it from UaExpert not from python.
Thanks.

https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples/client_to_uanet_alarm_conditions.py

Hi @AndreasHeine
It is giving some other output not the required event data.

Output:

New event received: %r Event(['AudibleEnabled:None', 'FirstInGroupFlag:None', 'InputNode:None', 'MaxTimeShelved:None', 'OffDelay:None', 'OnDelay:None', 'ReAlarmRepeatCount:None', 'ReAlarmTime:None', 'SuppressedOrShelved:None', 'BranchId:None', 'ClientUserId:None', 'ConditionClassId:None', 'ConditionClassName:None', 'ConditionName:None', 'ConditionSubClassId:None', 'ConditionSubClassName:None', 'Retain:None', 'EventId:None', 'EventType:None', 'LocalTime:None', 'Message:None', 'ReceiveTime:None', 'Severity:None', 'SourceName:None', 'SourceNode:None', 'Time:None', 'ActiveState:None', 'ActiveState/EffectiveDisplayName:None', 'ActiveState/EffectiveTransitionTime:None', 'ActiveState/FalseState:None', 'ActiveState/Id:None', 'ActiveState/TransitionTime:None', 'ActiveState/TrueState:None', 'AudibleSound:None', 'EnabledState:None', 'EnabledState/Id:None', 'LatchedState:None', 'LatchedState/FalseState:None', 'LatchedState/Id:None', 'LatchedState/TransitionTime:None', 'LatchedState/TrueState:None', 'OutOfServiceState:None', 'OutOfServiceState/FalseState:None', 'OutOfServiceState/Id:None', 'OutOfServiceState/TransitionTime:None', 'OutOfServiceState/TrueState:None', 'SilenceState:None', 'SilenceState/FalseState:None', 'SilenceState/Id:None', 'SilenceState/TransitionTime:None', 'SilenceState/TrueState:None', 'SuppressedState:None', 'SuppressedState/FalseState:None', 'SuppressedState/Id:None', 'SuppressedState/TransitionTime:None', 'SuppressedState/TrueState:None', 'AckedState:None', 'AckedState/FalseState:None', 'AckedState/Id:None', 'AckedState/TransitionTime:None', 'AckedState/TrueState:None', 'ConfirmedState:None', 'ConfirmedState/FalseState:None', 'ConfirmedState/Id:None', 'ConfirmedState/TransitionTime:None', 'ConfirmedState/TrueState:None', 'Comment:None', 'Comment/SourceTimestamp:None', 'EnabledState/EffectiveDisplayName:None', 'EnabledState/EffectiveTransitionTime:None', 'EnabledState/FalseState:None', 'EnabledState/TransitionTime:None', 'EnabledState/TrueState:None', 'LastSeverity:None', 'LastSeverity/SourceTimestamp:None', 'Quality:None', 'Quality/SourceTimestamp:None', 'NodeId:None'])

[MadTheT]

Hi Saleem344,
I have the same problem with subscribing to events as you that no data a send by the server (Wireshark debug shows that there are really no data send by the server). I use an ARSim Server by B&R. I can provide the wireshark logs if necessary. My guess is that im doing something wrong by the connection establishing or in the subscription settings.
I tried with the RnCommtest (https://github.com/br-automation-com/RnCommTest-Windows) which works fine.

Have you solved your problem?

Thanks

[danmoser]

Folks, FYI a recent issue I faced with a TwinCAT server is similar to the problem described here: #1205