Professional OPC
Development Tools


Online Forums

Technical support is provided through Support Forums below. Anybody can view them; you need to Register/Login to our site (see links in upper right corner) in order to Post questions. You do not have to be a licensed user of our product.

Please read Rules for forum posts before reporting your issue or asking a question. OPC Labs team is actively monitoring the forums, and replies as soon as possible. Various technical information can also be found in our Knowledge Base. For your convenience, we have also assembled a Frequently Asked Questions page.

Do not use the Contact page for technical issues.


14 Nov 2017 10:40 #5657 by support
Replied by support on topic Subscription

can you please post here the code of your notification handler? I want to check whether it takes care of all alternatives.

SubscribeMonitoredItem takes more general arguments which allow it to be used both for data changes (that is what you are interested in) or for event notifications. In your case, it is better to use SubscribeDataChange because it has all kinds of overloads that all are designed to subscribe to data changes.


Please Log in or Create an account to join the conversation.

13 Nov 2017 14:15 #5655 by I-Tecnology
Subscription was created by I-Tecnology
I have a problem with Subscription.
Here my code:
 string nodePlc = + "." + this.device + "." + nodeId;
 UANodeId nodeID = new UANodeId(ns, nodePlc);
 UANodeDescriptor nodeDescriptor = new UANodeDescriptor(nodeID);
 handleSubcription = easyUAClient.SubscribeDataChange(endPointDescriptor, nodeDescriptor, updateRate)

With this code I make a subscription to an item (a bit value).
It seems all is ok, as I start my programm it works fine. But if there are no changes for about 1minute, next changes are lost. No more changes are detected
Do you have any ideas of the problem?

I'm using latest version of OpcLabs library (today I download it to upgrade).
Framework is 4.5.2
OPC server is Topserver 5.16.728

I have also used this ( but nothing has changed):
handleSubcription = easyUAClient.SubscribeMonitoredItem(
                                 new EasyUAMonitoredItemArguments(
                                    new UAAttributeArguments(endPointDescriptor, nodeDescriptor)));
Whitch is the difference beetween SubscribeDataChange and SubscribeMonitoredItem?

best regards

Please Log in or Create an account to join the conversation.

Moderators: support
Time to create page: 0.166 seconds