IMAQdx GetImage2.vi and CalculateFramePerSecond.vi - low frame rate

[Yuri94]

Hi everyone,

Part of my VI deals with image acquisition. The implementation was taken from the example NI-IMAQdx "Grab and Attributes Setup". I've been trying to understand what the issue could be from the manuals, but no good so far. 

I have a continuous acquisition configured for 10 buffers as below:

The Buffer Number Out from the GetImage2 VI seems to output a frame rate that is much faster than 10fps. When I use the CalculateFramesPerSecond.vi,  it says I am acquiring approx. 25fps but only processing 10fps. This 25fps seems to be how fast the Buffer Number Out is counting. I don't quite understand the difference between the two outputs.

Since the Image Out port from GetImage2 is the one that goes ahead to the part where I process the images, I don't understand if I am actually getting 25fps or 10fps during processing.

Furthermore, I don't really understand the slower count "ActualBufferNumber" that is 'attached' to the event structure and goes into GetImage2. I've tried removing this connection, but the fps behaviour continued to be the same apparently.

Perhaps I've misunderstood how buffering works in a Grab setup like this. Any explanation will be helpful!

Thanks a lot!

[Yuri94 · Accepted solution]

Hi folks,

I've found the issue.

The whole loop was within a structure updating only every 100ms. After I changed it to update every 20ms, both the processed and acquired frame rates matched.

Cheers,

Yuri