Has anyone triggered a Camera Link Camera using the framegrabber?

[TonyDarnell]

Hello,

I'm trying to trigger a camera link camera to take high speed exposures. I have a PCI-1428 camera link board and LabVIEW 6.1 on a windows 2000 machine.

Everything I've read says that the way to do this is to perform a synchronous trigger acquisition where I send a trigger to both the framegrabber and the camera.

My question is, I thought the trigger lines on the PCI-1428 went both ways, they are can be an input and an output. So, can I trigger the camera with the framegrabber to tell the camera to take an image, then grab the resulting image from the framegrabber using Grab Acquire.vi?

Or, do I have to trigger both the camera and the framegrabber simultaneously to get a triggered image?

The latter doesn't make sense to me if I can trigger the camera with the framegrabber, why would it (the framegrabber) need to be triggered?.

Thanks for any help, I've been triggering the camera with the framegrabber for some time, but I can only run the camera at 15hz this way and I know I can double it because others have run this same camera at 30hz using the Matrox Camera link card.

Regards,
Tony

[ColinAE]

Hello.

It sounds like you are currently setting your camera into triggered mode, sending triggers to the camera from your 1428, and acquiring those images.

Triggered image acquisition can be a bit of a tricky subject, because the triggers can be sent to BOTH the camera AND the IMAQ device. The question always becomes: Which one do I use when? Needless to say, the answer is not trivial, as it depends a lot on the camera and the application. I will attempt to explain when each type would be used, and thus hopefully help answer this question.

Digital cameras typically run in either a 'free-run' mode (continuously taking images), or in a triggered (or asynchronous reset) mode. In free-run, images are constantly being output on the data lines to the IMAQ device, whereas with triggered mode the image data (and assoicated handshaking signals) are only sent when a trigger is received. Knowing this fundamental behavior, we can then look at the two basic types of triggered acquisitions.

1. Trigger sent to camera, framegrabber in normal mode (Grab, Sequence, Ring)
   In this case, the framegrabber is simply waiting for the images to be sent from the camera (i.e. waiting on the handshaking signals), so it does not need to be setup for any triggering. Whenever the camera receives a trigger, the image is taken and sent to the grabber, where it is acquired as if the camera was running normally.


2. Trigger sent to framegrabber, camera in free-run mode
   In this case, the camera is constantly sending images to the framegrabber. When the grabber receives a trigger, it marks the image as a 'good' image and it is then acquired. This method is the one that is used most commonly with analog cameras, as they usually need to be in a free-running state.

There are definitely some other iterations to the above scenarios, but that should give you an idea of the general functionality.

In your case, I would try to send triggers directly to your camera, and setup the acqusition to be a standard grab, ring, or sequence acqusition.

Hope this helps.
Regards,
Colin C.
Applications Engineering

[TonyDarnell]

Colin,

Thanks for the response and the clarification. Yes, I knew about the two modes of operation of the framegrabber and the camera and you helped to clarify that- thanks. My question though is this:

I have my camera running in triggered asynchronous reset mode. I want to trigger an image and recieve it at 30hz in LabVIEW 6.1 (the camera can do this, it's being done on a Matrox framegrabber under IDL and I'm sure the 1428 can do it too). What is the best way to trigger the camera? I've been doing it through the T0 trigger line on the PCI-1428 but I'm not able to get the framerates I want this way. Should I trigger the camera using some other source, such as the PCI-6733 DAQ board that is also installed on this computer?

I'm setting the 1428 up for a Grab Acquire acquisition and then sending triggers to the camera from Trigger Line 0 on the card. Is this not the ideal way to trigger, since the trigger lines go both ways? Every example on the NI site shows triggering from an external source which has confused me since the card can do it.

Thanks so much for your help.
Tony