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EasyDAClient asynchronous or synchronous

02 Jul 2022 17:55 #11027 by support

The API (methods) for reads/writes on the EasyDAClient are synchronous. Internally, QuickOPC selects *some* method to perform the operations, depending on which interfaces the OPC server provides. By default, asynchronous OPC calls are preferred.

The answer to your questions depends on what actually is meant by the word "fully" in "This ABB OPC server does not fully support asynchronous (subscriptions) OPC operations.".

If the interfaces for asynchronous reads/writes are not supported by the server at all, QuickOPC will select the synchronous interfaces, and the read/write methods you listed will work fine. Only if the OPC server has somehow "incomplete", non-functional implementation of the async interfaces, it would be necessary to do more. QuickOPC has settings to enforce the synchronous operations, which I can help you with. But there is no reason to do that unless you are having problems. Have you tried the methods you listed, and what were the results?

Best regards
The following user(s) said Thank You: mlebelle

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30 Jun 2022 05:02 #11020 by mlebelle
We are using the easydaclient in a Visual Basic 6 development environment. We need to communicate with an ABB OPC server. This ABB OPC server does not fully support asynchronous (subscriptions) OPC operations. So we want to make sure that we use synchronous OPC operations only. We are using the following functions of the easydaClient. Are these functions asynchronous or synchronous operations and how can we force them to be synchronous or do we need to use other functions?


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