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Connect and disconnect.

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14 Nov 2015 10:06 #3659 by support
Replied by support on topic Connect and disconnect.
QuickOPC works differently. There is no way to directly, explicitly control connections or disconnections. All you care about are the actual operation you want to perform (reading, writing, subscriptions, etc.), Connections are "invisible" to you. The connection remains open for a "hold period" after an operation; the hold period can be configured from the code if necessary, but that should remain reserved only to situations where the default behavior proves to be sub-optimal.

For more info, read the Concepts document - it is installed with the product, or downloadable from www.opclabs.com/resources/documentation .
  • Chapter 4.7: Connection-less Approach
  • Section 13: Best Practices
Basic operations:
  • Section 5: Procedural Coding Model
Best regards

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14 Nov 2015 09:35 #3658 by pvs
Connect and disconnect. was created by pvs
I am evaluating EasyOPC.
From my experience with an other connectivity tool I am used to the sequence:
- connect to a server at the start of the application
- read and write asynchroneous from and to the server or on notification.
- disconnect from the opc-server just before or at closing of the application.

My first test used repetitive reading of a tag with EasyDAClient1.ReadItemValue.
This function seems to include an implicite connection to the server as soon as it is called.
Is this correct? What will happen with the connection in case of a pauze in reading? Will the connection remain in place for some time?

I have two questions:
1. Where can I find the documentation for the basic functions: connect, set notification, read a variable, read a vector or array, write a variable, write a vector or array, disconnect for an DA server?
2. What code should I use for an explicite connect and disconnect?

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