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

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