Best possible way of Acqustion with Low-Level Vi

[emilroz]

Hi,

I have a question. I just started using labview. Am writing an application which main purpose is to acquire images. I'm using 8.9 fps CCD camera however using low-level Vis I can aquire only 7 fps.

For the test I used  One Shot Mode with 9 allocated buffers and then I simply saved all 9 images. This however takes longer then the camera specs. I noticed that if I simply get the images one-by-one it takes almost 300 ms to get first one and then 110 ms for the rest, which is extacly the camer specs.

My question is does anyone one where is this 200ms lag on the first image coming from, or if there's a better way for fast acquistion.

I'm using LabView 2009 version.

Emil

[sahpe]

Hello Emil,

Did you build your code from scratch or are you using code from the NI Example Finder? If it's an example then please let us know which one you are using, otherwise please post your code so that we can have a look. If you are seeing the lag from the instance you hit run then this is probably expected and it might mean that you need to configure a triggered acquisition.

I hope to be able to help further when I see your code.

Kind Regards,

Michael S.
Applications Engineer
NI UK & Ireland

[emilroz]

Hi Michael,

I'm not using any example codes. The code I'm running is dead simple (attached below).

Thanks

Emil

[sahpe]

Hello Emil,

The type of acquisition you want to achieve is dempnstrated in an example that ships with the IMAQdx driver set. Fire up the LabVIEW Example Finder, and navigate to this:

Hardware Input and Output> IMAQdx> Low-Level> Low-Level Sequence.vi

In this example you will see what the necessary steps are to get a one-shot acquisition. Essentially, you will need to preallocate the buffers, and then write to them. The rate can be determined by the timing you apply to the second For Loop I believe. Loops are a much better programming practice in LabVIEW compared to sequence structures.

Try it and let me know how you get on.

If you require further assistance, please post your VI instead of a picture, or alternatively post a snippet.

I hope this helps,

Kind Regards,

Michael S.
Applications Engineer
NI UK & Ireland