QuickOPC won't return values with Bad quality, with one exception and that is when the status field in the quality is OPC_QUALITY_LAST_KNOWN.

Hello,
thank you for answers.

"Bad, device failure" in Matrikon Client is probably the same as "DeviceFailure LimitLow (13)" you are seeing through QuickOPC (LimitLow is a sub-status which Matrikon may not show).

For any "Bad" quality (with exception of Last Known Value status), in OPC "Classic", the OPC server is basically allowed to send garbage in the Value. The clients must generally not interpret the value in case of "Bad" quality, because the value is not guaranteed to mean anything. QuickOPC sets the value to 'null' with Bad qualities (except Last Known Value) to prevent the users from making the mistake of using it. If there is a problem but still a value, the server should use "Uncertain" quality.

Best regards

Hello.

By design, QuickOPC does not modify or create "own" quality values. If you have received 'DeviceFailure LimitLow (13)', then I am convinced that it must be the quality that came from the OPC server.

Questions:

1. Which target OPC server are you connecting to?
2. In QuickOPC, are you using ReadXXXX, or subscriptions?
3. When you say "when i check tags in Matrikon ", do you mean some Matrikon client, or what, and how precisely do that? (again, among other things, I am trying to figure out whether you are using subscription or reads, or perhaps looking at the values right on the server side).
4. Do you always get this quality form some tags, or are you saying that they generally work OK, but give this quality from time to time?

A bug in this respect in QuickOPC is quite unlikely. I have suggestions prepared that depend on your answer. If everything else, OPC Analyzer can be put between the client and the server, which would show what is actually happening between the two.

Regards