missing data in Subscription

[xyzakdkd]

Hello, After establishing a connection to an OPC UA server using subscription, data retrieval appears to be functioning smoothly. However, when i compare the data obtained from my script with that data using the (UaExpert Software) Datalogger. Notably by running both for 3 hours, i get missing data on my client script. In the table you can see that the bold value is missing

Data from the DataLogger

x	xxx	value	xxx	source_timestamp	server_timestamp
1	0x000b	72.5	0x00000000	2024-05-13T13:59:07.753Z	2024-05-13T13:59:07.784Z
2	0x000b	72.40000153	0x00000000	2024-05-13T13:59:08.999Z	2024-05-13T13:59:09.084Z
3	0x000b	72.30000305	0x00000000	2024-05-13T13:59:10.568Z	2024-05-13T13:59:10.584Z
4	0x000b	72.19999695	0x00000000	2024-05-13T13:59:12.001Z	2024-05-13T13:59:12.084Z
5	0x000b	72	0x00000000	2024-05-13T13:59:15.189Z	2024-05-13T13:59:15.284Z
6	0x000b	71.80000305	0x00000000	2024-05-13T13:59:15.690Z	2024-05-13T13:59:15.785Z
7	0x000b	71.69999695	0x00000000	2024-05-13T13:59:16.065Z	2024-05-13T13:59:16.087Z
8	0x000b	71.5	0x00000000	2024-05-13T13:59:16.627Z	2024-05-13T13:59:16.685Z
9	0x000b	71.80000305	0x00000000	2024-05-13T13:59:17.002Z	2024-05-13T13:59:17.085Z
10	0x000b	71.90000153	0x00000000	2024-05-13T13:59:17.004Z	2024-05-13T13:59:17.087Z
11	0x000b	72.09999847	0x00000000	2024-05-13T13:59:17.252Z	2024-05-13T13:59:17.285Z
12	0x000b	72.40000153	0x00000000	2024-05-13T13:59:17.502Z	2024-05-13T13:59:17.585Z
13	0x000b	72.59999847	0x00000000	2024-05-13T13:59:17.753Z	2024-05-13T13:59:17.784Z
14	0x000b	72.80000305	0x00000000	2024-05-13T13:59:17.876Z	2024-05-13T13:59:17.886Z
15	0x000b	73.09999847	0x00000000	2024-05-13T13:59:18.003Z	2024-05-13T13:59:18.088Z
16	0x000b	73.30000305	0x00000000	2024-05-13T13:59:18.375Z	2024-05-13T13:59:18.387Z

Data from my script

[AndreasHeine]

you need to post the subscription and monitored item settings!

[xyzakdkd]

can you please give me an example

Subscription part

async def create_subscription(client, handler):
    try:
        subscription = await client.create_subscription(500, handler)
        handler.subscription = subscription
        for node_id in nodes_list:
            node = client.get_node(node_id)
            await subscription.subscribe_data_change(node, queuesize=1)
    except (ConnectionError, ua.UaError):
        _logger.warning("Error creating subscription")

[AndreasHeine]

might be the queuesize!

[xyzakdkd]

i change it to 0 and still get missing data

[AndreasHeine]

what are the settings of UAExpert? tbh dataloss is very unlikely due to the fact that the server fill the queue and the client recv all queued changes within one response. i bet its just a setting thing!

[xyzakdkd]

I try it to change the setting on the UAExpert. are this the same as the default setting in asyncua? all i need to add is the Sampling interval

my code

async def create_subscription(client, handler):
    try:
        subscription = await client.create_subscription(100, handler)
        handler.subscription = subscription
        for node_id in nodes_list:
            node = client.get_node(node_id)
            await subscription.subscribe_data_change(node, sampling_interval = 250)
    except (ConnectionError, ua.UaError):
        _logger.warning("Error creating subscription")

[xyzakdkd]

Thanks @AndreasHeine you were right, it was just a setting thing

[AndreasHeine]

@xyzakdkd glad i could help!

[xyzakdkd]

Hello @AndreasHeine i was trying the whole week to test it, it sometime give the same data as the UA-Expert but in many time i get more data in the UA-Expert. Where could be the problem. or could be a problem with the server.

In the code:

async def create_subscription(client, handler):
    try:
        subscription = await client.create_subscription(200, handler)
        handler.subscription = subscription
        for node_path in x:
            node = client.get_node(node_path)
            await subscription.subscribe_data_change(node,  queuesize=10, sampling_interval=250)
    except (ConnectionError, ua.UaError):
        _logger.warning("Error creating subscription")

CreateSubscriptionResult(SubscriptionId=2156708, RevisedPublishingInterval=200.0, RevisedLifetimeCount=10000, RevisedMaxKeepAliveCount=3000)

UA-Expert Setting