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Node IDs containing slashes

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24 Jan 2023 13:08 #11451 by support
Replied by support on topic Node IDs containing slashes
Hello.

In OPC UA terms, a subscription has parameters such as sampling interval, and comprises of one or more monitored items that share the same parameters (and publishing mechanism). So, even with just one subscription, it is possible to subscribe to multiple monitored items, as long as they share the same subscription parameters.

This server indeed supports only one subscription per session, and that is the cause of the problem, because your subscription(s) cannot coexist together with our internal status subscription.

In UaExpert you have probably simply subscribed to multiple nodes on the same subscription in the "Data Access View", which of course works OK. But you can easily see in UaExpert that only one subscription is supported: After subscribing to one node, do Document -> Add, select "Data Access View", and press Add. This will create a second tab, labeled "Data Access View-1". If you now put a node into it, you will immediately get BadTooManySubscriptions.

It should also be noted that the server declares itself (in its ServerProfileArray) as supporting the "EmbeddedUA" profile. But this profile requires that at least 2 subscriptions per session are available. The proper profile for this server should be "MicroEmbeddedDevice".

The question remains, why did not disabling the status subscription help? I suspect you may not be doing it right. Please post the related pieces of code here, and I wil check them.

Best regards

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24 Jan 2023 09:43 #11449 by Lars Otte
Hello,

sorry I just noticed I posted in the wrong section, we're using .NET and not COM... It should belong here: opclabs.com/forum/ua-reading-writing-subscriptions

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23 Jan 2023 13:12 #11448 by Lars Otte
Hello,

it seems that the slashes are indeed not the issue. Reading works fine. And subscribing to nodes with an integer identifier also results in TooManySubscriptions.

I've disabled the status subscription using the SessionParameters, but it didn't resolve the issue. The server shouldn't have a limit, and using UAExpert, I am able to subscribe to multiple nodes simulaneously.

We're using QuickOPC 2021.02 and were using an "ADAM-6317"...

I'll send you an url to a test server, is it possible, that you have a look into it?

Best regards

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22 Jan 2023 09:08 #11447 by support
Replied by support on topic Node IDs containing slashes
Hello,
it is unlikely that the cause of the problem are the forward slashes in the node IDs. It is not a reserved character, nor is treated in any special way.

To verify that the slashes are not the cause, you can try:

1. Do a Read instead of Subscribe. I suppose it won't give “Too Many Subscriptions”?
2. Try to Subscribe to a node *without* the forward slashes. It can be some node in the namespace zero. Try simply "i=2258" (which is the CurrentTime). I suppose it will also give “Too Many Subscriptions”, even though there are no forward slashes?

Anyway, if this is a small embedded device, it is possibly that it supports just one subscription; two may already be too many. QuickOPC, however, normally always creates a subscription for internal purposes - status monitoring. So your own subscription is already a second (or third, ...).

Set static EasyUAClient.AdaptableParameters.SessionParameters.EnableStatusSubscription to 'false' to turn the status subscription off (or, if you are setting easyUAClient.Isolated to 'true', the setting needs to be done in EasyUAClient.IsolatedParameters.SessionParameters). Does it help?

Also, can you please answer following questions:
1. Which QuickOPC version are you using?
2. Which device/model are you connecting to?

Best regards

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20 Jan 2023 10:31 #11446 by Lars Otte
Hello,

Currently we‘re adding a new device, which uses OPC UA and has a different naming scheme for the node IDs. The IDs contain forward slashes instead of dots, for example: “ns=1;s=/ObjectsFolder/DigitalInput/DI_02_DIValue”.

When we subscribe to a node, we get an error status code “Too Many Subscriptions”. But using UA Expert, subscribing to the node works fine and the server should not limit the number of subscriptions.

Is the slash a reserved character for QuickOPC, and does QuickOPC do anything special with it, which might cause the error status code?

Best regards,

Lars Otte

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