Hello.

Is it really e.Vtq.Value that is null, or is it actually already the e.Vtq that is null?.

If e.Vtq is null: In this case, e.Exception is not null, and contains the exception object that describes the problem. Please examine this exception object (e.g., its Message property), to obtain further details.

If e.Vtq is non-null but e.Vtq is null: In this case, most commonly it is a "bad quality" data being delivered by the OPC server. Please examine e.Vtq.Quality. If it is a Bad quality, then there is no usable Value to speak of, and that's why it is null. In this case, we are delivering you the Vtq as it was sent to us by the server. You would therefore need to investigate on the server side for the cause of the Bad quality.

Mfg
Zbynek Zahradnik