Professional OPC
Development Tools

logos

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.

EasyDAClient asynchronous or synchronous

More
02 Jul 2022 17:55 #11027 by support
Hello.

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

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

More
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?

client.ReadMultipleItems(arguments)
client.WriteMultipleItemValues(arguments)
client.WriteItemValue

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

Moderators: support
Time to create page: 0.061 seconds