vision assistant after camera trigger

[nirefa]

I have a project which in I have to analyze camera image. Camera create image in trigger mode and with external sensor. I have used Vision Acquisition & Vision Assistant functions in sequence structure.  I want Vision assistant is done just when camera capture a new image

Vision Acquisition does not any output when it is executed (this function doesn’t have enable out)

Can you help me?

I have to use event case with value change of image output?

Thanks

Reza

[Danubio]

Hi Nirefa,

You could use a shift registers to store the actual image and compare it with the one from the previous while loop iteration using a boolean comparison function, that way you could enable a case structure to execute the Vision assistant VI. 

However, I highly recommend you that if you want to develop custom functionalities, start getting familiar with the vision VIs instead of using the express VIs only, since these are not intended to be used in more complex/flexible algorithms/architectures, but the vision VIs will provide you this programming flexibility.

I hope this helps! Best regards,

Daniel C.

[BlueCheese]

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@Danubio wrote:

You could use a shift registers to store the actual image and compare it with the one from the previous while loop iteration using a boolean comparison function, that way you could enable a case structure to execute the Vision assistant VI. 

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You have to be careful with using Image datatypes in this fashion. Since it is a refnum and not a value datatype, they operate a bit differently. Specifically, out of the Vision Acquisition Express VI, you might get the exact same image refnum each time it is called (depending on your configuration) and only the image content the refnum points to will have changed. You have to do something explicit to copy the image data itself and compare it.