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Using ChangeDetectionEvent with NI USB-6259

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i am very new to labview and LabWindows, so this might be very trivial to solve.

I would like to perform an action ( change some UI element ) when ever I receive a rising edge from a TTL signal.


I hoped to achieve this by following the ReadDigChan-ChangeDetectionEvent example, and defining a DAQmxRegisterSignalEvent() for rising edge on one of the Digital input lines, but I even fail to use the example for my

USB-6259 (BNC).


When I try to perform a Change detection on any of the lines of port 1 and 2 I get


Lines specified do not support change detection.  Select lines that support change detection. Device: Dev1 Physical Channel: port1/line0  Task Name: _unnamedTask<0>  Status Code: -201020

Do I missunderstand something? Should the Digital In ports on the 6259 support change detection?


When trying the same with port0 the application freezes for a long time and than just throws out a message saying that

DAQmxReadDigitalLines() timedout.


I hope that is enough information to answer the question. If not what else do you need?


thank you,


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Accepted by topic author PasiekaM


it seems the USB-6259 does not support change detection.



Digital Change Detection in NI-DAQmx


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Hello DanielMorris,


hmm, that I would not have expected. Following the error message it might make sense, but the NI documentation you linked is kinda vague to me.


In addition I saw that using the NI MAX tool and looking at the Device Routes there is a "Direct Route" between the ChangeDetectionEvent and the different PFI0-16 lines. ( dont know if this is of importance, though )


Well my work around is to use a counter to performe edge counting, and a timer and polls the counter value.


Thank you!

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