Hello.

QuickOPC maintains connections to target OPC servers automatically. The connection is created when first needed, and closed some (configurable) time after not being in use any longer. In case you create OPC A&E subscriptions, they indicate an intent to be subscribed, so in this case the connection is kept open, until you unsubscribe all of them. This behavior cannot be changed, and there is no additional call to disconnect explicitly.

Related info: opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...0OPC%20failure%20recovery.html

Regarding the first question: The information about whether the server is or is not successfully subscribed is transferred through the same channel as the A&E event notifications themselves. See e.g.: opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...html#Notification%20Event.html

Also related:
- opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...ibing%20to%20OPC%20Events.html
- kb.opclabs.com/OPC_A%26E_Notification_Handler_Pseudo-Code

Best regards