Subscriptions work similarly to async operations. It is therefore likely that if the async reads does not work, subscriptions won't either. I suggest you test it out too, though. My aim was to narrow down the possible cause, and possibly provide a workaround for the Read, and we have that now.

If you need the subscriptions and they don't work, you need to look further in the DCOM configuration area. Make sure that DCOM allows access to the CLIENT by the SERVER (i.e. the reverse of the usual way), because that's what the async operations and subscription need for callbacks. Also, try a different settings for:

1.EasyDAClient.ClientParameters.UseCustomSecurity
2.EasyDAClient.ClientParameters.TurnOffActivationSecurity
3.EasyDAClient.ClientParameters.TurnOffCallSecurity

Best regards

its working with synchronous mode, but what about subscribeItem is it synchronous or asynchronous?

Can you try switching the reads to synchronous?

You can switch to sync-only by setting (on EasyDAClient object) the InstanceParameters.Mode.AllowAsynchronousMethod property to 'false'.

Best regards

Any ideas for this?

1. Remote, but in same network
2. Console App
3. From what i know all readings are asynchronous, but i cant check source code, so im not 100% sure
4. just InstanceParameters.Timeouts.ReadItem, i was trying with diffrent timeouts, but same exception

This is, basically, a timeout.

Can you please answer this:

1. Is the server local or remote?
2. What kind of app are you developing? (Windows Forms, ASP.NET, Windows Service, ...)
3. In the other apps, can you select between Synchronous and Asynchronous reads? Do Asynchronous read work?
4. Are you setting any parameters on the EasyXXClient object?

Thank you

Hi,

ive started to use your dlls (eval at the moment) and im trying to read some data from Tac OPC server.
I can see all branches etc, but when i try to read any data from Item ive got an error:
"Read not completed. This error indicates that it could not be verified that the requested read operation was completed during the timeout period. It is possible that the read operation will actually succeed or fail, but later. Increase the timeout period if you want to obtain positive or negative indication of the operation outcome. Other reason for this error may be that under heavy loads, topic request or response queue is overflowing. Check the event log for queue overflow errors (if event logging is supported by the product and enabled)."

I can read from other apps, so there is no problems with OPC Server, i can also read Properties from Item, but cant read value(ReadItemValue or ReadItem). I was using your console example (C#).

Regards,
Piotr