Trouble synchronising snap with external trigger

[RockChang]

I have a Dalsa camera with a pci-1424 frame grabber set up for image acquisition. A terminal sends a signal to both the frame grabber and a light source so to illuminate the region of interest at the correct moment.

It seems that the frame grabber is acting too slow (>1ms) and is not synchronised with the frame grabber. Furthermore, the time differential is not a constant.

I have no problems doing this with IMAQ Vision, however I would like a labview VI that will give me greater flexibility in my image processing. Even the Vision option to write a VI produces the same result, nor do the NI acquisition examples such as LL and HL triggered snap.

My only guess is that somehow I am not performing an asynchronous
acquisition.

The attached file is simply the script that Vision puts together for a trigger acquisition

Any help is greatly appreciated.

[Dustin_W]

I agree, it doesn't sound like you are performing an asynchronous acquisition, but rather just grabbing the next available frame. I would make sure your camera is set up for asynchronous reset mode. If this is not set, the camera continuously acquires, and when the trigger is seen the next available frame is accepted by the frame-grabber. When it is set, as soon as the camera recieves the pulse it starts a new frame. Check your camera documentation on how to set up the camera in asynchronous reset mode, usually there are timing diagrams that can also be used to set up any delay needed between your flash and the acquisition.

Also, you probably want to be triggering the camera rather than the framegrabber itself.

[RockChang]

Thanks for your response. All your recommendations were already checked beforehand. The problem it turns out was a rather simple one. The VI written by vision itself was the fault. It preforms two snaps, when only one is required. The second snap overwrites the first. All I had to do was remove this second snap.