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PCIe-1427 : flexible use of digital I/O during image acquisition

Hi,

 

I am using a pcie-1427 framegrabber to acquire images (@10Hz so pretty slowly) using a PhotonFocus camera.

 

I would like to use the digital lines of the PCIe framegrabber to trigger an external stimulator, but only on a certain number of frames, not the entire acquisition. I find, in the manual it should be said that these lines are not as easy to use as basic digital I/Os.Smiley Sad

 

I have seen this post about using the digital I/O:

http://forums.ni.com/t5/Machine-Vision/Output-channel-on-NI-PCIe-1427/m-p/534723

 

What I would like to do is :

During a 100 frame acquisition, the first 40 should provide the baseline signal (no stimulus), the next 60 should acquire the signal due to stimulation and should hence output a digital signal to the stimulator.

 

I could not find an easy way of starting the trigger line during the acquisition. Is this possible ? Are these lines strictly related to the image acquisition ?

If this is the case, I thought of doing a "40 frame acquisition alone" followed (as fast as possible) by a "60 frame acquisition + digital line" but this does not seem very elegant or precise.

Another way would be to use one of our small USB DAQs, but they are not very precise in their timings.

Any suggestions ?

 

Thanks

 

 

 

 

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UP

 

Nobody used these lines to do something similar ?

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From my understanding there are two options:

 

 

  1. use the IMAQ Generate Pulse3 VI to generate immediate pulses using software timing out of you grab loop
    + easy to implement
    - jitter through software timing

  2. aquire 40 images, stop the acqu and start a 2nd acquisition task with hardware generated pulses (see C:\Programme\National Instruments\LabVIEW x\examples\IMAQ\IMAQ Signal IO.llb\LL Pulse Generation.vi)
    + exact hardwaretimed pulses
    - delay between image 40 and 41

 

Hope this helps,

Andreas Stark
Senior Transportation Systems Engineer
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By modifying the GeneratePulse3.vi I managed to control the digital output exactly like I wanted. The framerate being low and the pulses being generated relative to the cameras framerate the endresult is pretty precise, at least enough for our purpose.

 

Thank you for your help

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