Hello,

Another thing related to this issue. I got it to subscribe, as I mentioned.
When I install the service, it does subscribe but when the tag value changes, it does not call the callback method. Also, when I try to write to any tag, I get a timeout exception.

Here's the inner exception message:
"Write not completed. This error indicates that it could not be verified that the requested write operation was completed during the timeout period. It is possible that the write 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)."

In Debug it works fine, but when I build it for release and install it (as a network service), then this issue comes up.

Thank you for your time.

*******EDITED******
Just got it working again. It turns out I hadn't done the appropriate DCOM configuration. And yes, I had to release it as LocalSystem Service. All is well now.
Hope someone finds this useful.

Hello,

The problem was the one you pointed out, the name of the OPC server actually was "CyProOPC.DA2" not "CyBroOPC.DA2".

Thank you or you time.

Yes, I have used the same approach many times and it has always worked fine (great product btw).

The machine I'm coding (and testing) is 64bit, and in visual studio the platform I have targeted is "Any CPU", not 32bit or 64bit specifically.
In fact, I just tested it by targeting 32bit and 64bit platforms, and still the same.

I'm trying to make a windows service to subscribe to tags, could this have anything to do with it?

Thank you for you time.

Thank you for the fast reply.

Here's the line for subscribing:

OPCClient.SubscribeItem("", "CyBroOPC.DA2", "CyBro-2.12345.cybro_qx00", 1000, tagc);


where 'tagChanged' is the callback method. Of course this is just a test code line I used to quickly check if everything is OK.

The OPC server i local, here "" for the machine name.
"CyBroOPC.DA2" is the name of the OPC server.
"CyBro-2.12345.cybro_qx00" is the tag
1000 is the refresh rate.

Any ideas?

Greetings everyone,

I'm developing a Windows Service, which will have a single EasyDAClient for subscribing/writing/reading from/to the OPC Server.
When I try to subscribe, the subscription is done without any error, but when it calls the callback method, I get the following error:
"[12585987] *** System.Runtime.InteropServices.COMException (0x8004001F3): Invalid class string"

Can anyone tell whats is this error related to? And how could I remedy the situation here?

Thank you in advance,
Rinor Berisha