Great - thank you for letting me know.

Best regards

Hello.

As long as the thing starts communicating OK, I am not aware about any virus scanner issues, or a need to configure the virus scanner.
There is no separate process. The QuickOPC components run inside the process that instantiates the objects - that is, in your application.

Some questions:

1. When you say "...slows down periodically...", is there truly an observed, more or less regular period in which it happens, or is it random?
2. When it happens, does the slow-down affect all communications, or just some? If everything had appeared "blocked", one possible cause would be the .NEt GC (Garbage Collector).

Best regards

Hello.
The code snippets you provided are correct for what you intended to achieve.

The OPC asynchronous method are meant to allow the client proceed with other work, while the server fulfills the request. The EasyDAClient does not, however, expose asynchronous API to make use of this. All ReadXXXX and WriteXXXX method calls on EasyDAClient are synchronous. Even if OPC async calls are used internally, the way the programmer "sees" them through EasyDAClient is synchronous.

I do not expect any measurable speed difference between the two approaches.

Best regards

Do I understand it correctly that you are connecting to just one Kepware server? The remainder of my answer is based on this assumption; let me know if the assumption is not correct.

With the default settings, yes, no matter whether use just one EasyDAClient instances or multiple instances, connections to the same server will be shared - so there will be just one connection.

If you want separate connections, set the Isolated property to 'true'. From the code you posted earlier it looks like that you are doing so, so if this is the case on (all) your EasyDAClient instances, then there will be separate connection to the target OPC server for each of them.

The issue you are observing (random delays), however, may be on the server side, and not related to one operation "blocking" another. If you keep getting it with all Isolated=true settings, one way to find out more would be to use OPC Analyzer and check how long it takes the server itself to respond.

Best regards

Hello.

Your code does multiple things, but yes, what you have done should force the component to do synchronous reads/writes only.

Regarding the remaining questions, is there any issue with cleaning up, or what is it that you are trying to achieve? Normally, it should be enough to set the g_opclabs to variable to whatever is the equivalent of NULL in PowerBuilder.

Best regards