No error status available in NI-DAQ callback under Visual C++.NET

[CyberSmith]

I am actually not using measurement studio, but straight NI-DAQ and Microsoft Visual C++ .NET. Unfortunately, there is not a category for NI-DAQ.

I register a callback finction for event code 2 (transfer stopped or error). When I recieve the callback, I cannot find a way to determine what error caused the callback. It kills a long term continuous acquisition.

[rgharrison]

Hi CyberSmith,

It looks like I received your email in our Tech Support box as well. I will post a response here as well. Typically if the callback is associated with a DAQ Event you will only know if the operation completed or not by the second least significant byte of the wParam parameter of the DAQ Event callback. You will have to use another command such as DAQ_Check() which will return the state of the data acquisition process as an error code.

However, it sounds like there is a function in your callback that is returning an error. Is it that you interpolate that there is an error because no data is available or something similar or does a function actually return an error? Specifics of the exact function and sequence would help me understand bet
ter what could be causing the error and how to trap it effectively. Anyway, hope that helps. Have a good day.

Ron
Applications Engineering
National Instruments