You need to check the Exception property in the results. This will give more information about the cause of the problem.
Best regards

From: .....
Sent: Monday, October 17, 2011 9:57 AM
To: Zbynek Zahradnik
Subject: Data Acqusition Problems

Dear Sir/Madam,

We are using yout opc-lib to acqurire large amount of opc-items. I'm using MultipleRead for faster access. Each group constits of 600 Items max there're 5 groups total at the moment (so approx 2000 items total). The acuisition is nearly continuous, so a new cycle restarts short after the end of the previous cycle.

I've detected an issue that is as follows:

After a while (several hours of data-acquisition) the Vtq-Object of every item (in all groups) is NULL and i have to perform an Application.Restart() to get it work again.

Can you please provide me some help or additional information to this issue (maybe to detect an invalid opc-state and handle this within the application?)

Thanks in advance,
Br
M.