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Problem in using ChangeDetection Events.

Good morning.


I'm developing an application using LabWindows/CVI 2009 (Vs. 9.1.0 (428)) and I need to use the "Change Detection" interrupt to be warned as soon as possible of a variation of one or more digital lines on a port.


Using MAX, I have enabled the simulation of the following two boards:





Using the "NI Example Finder" tool, I found that both the boards can be used to run the "ReadDigChan" and the "ReadDigChan-ChangeDetectionEvent" examples. The "ReadDigChan" correctly works, i.e. I can see data on the example MMI (I can correctly see the LEDs enlightened following the algorithm realized by the NIDAQmx). Using the "ReadDigChan-ChangeDetectionEvent" I'm not able to see any variation in the MMI. Please note that:


    •  The example can be compiled correctly.
    •  The obtained executable runs without errors (no error returned by the used NIDAQmx routines).
    •  A "printf()" instruction inserted at the beginning of the "ChangeDetectionCallback" callback is never executed, i.e. it's like the "Change Detection" were never generated.
    •  The same behavior can be observed for both the simulated boards (PXI-6509, PXI-6528).


Any idea about possible errors in my operations? Is it possible that the change detection cannot be used in "simulation" mode?


Any help would be appreciated!


Thanks in advance, Massimo.



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Hi Massimo,


the first thing I've found is a document that explains why sometimes the change detection doesn't work as expected:


I don't think you problem is due to the use of simulated device, so maybe knowing the considerations of the previous document, everything will work right.


Hope it helps,


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