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Using ChangeDetectionEvent with NI USB-6259

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Hello,

 

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,

Manuel

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Accepted by topic author PasiekaM

Hello, 

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

 

Link:

Digital Change Detection in NI-DAQmx

http://www.ni.com/white-paper/4102/en/#toc1

 

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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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