unexpected frame rate

[guibook]

I'm using a PCI-1428 framegrabber and a Basler A501k.
in MAX, I set the frame rate to be 40 Hz (frame size is 1280*1024). when I do a grab acquisition in MAX, the achieved frame rate is only 26 Hz (acquired and displayed). If I set the frame rate to be 20 Hz, the achieved frame rate will be only 16Hz. The frame rate is imposed by an internal signal of the PCI1428. does anybody know what could be the reason of this incorrect frame rate? my first idea is that the timing for the internal signal is not correctly calculated in the Basler A501k.icd file, but I'm not sure to be right!

[visionpro]

I use PCI-1428 with a Dalsa Camera.
Using NI's Measurement & Automation Explorer to
display live video, you will see the displayed
framerate, that is lower than the camera's framerate.
The difference is due to the time taken in
transferring the video data across the PCI bus, that
is shared in the PC system.

To get short sequence of video at peak framerate, use
the ring buffer with max size on 1428 and also setup
a FIFO queue in PC memory. You can then move video
from 1428 to PC FIFO as fast as you can, and
process/save the video from the FIFO end at the
same time.

You will need at least several GB memory to accomodate
minutes long video at peak framerate.

G

[guibook]

I understand your point, but the PCI1428 and my PC can achieve higher rates than the one displayed. for example, when I ask for a 40 Hz acquisition, the MAX will do a 26 Hz but if I ask for a 20 Hz acquisition, the MAX will do a 16 Hz acquisition...although it's able to do a 26Hz acquisition... the *.icd file contains the following lines:
Action (PG) {
Line (0) {
Start (High)
1, 50000000 / (Frame Rate) * 10
}

Line (4) {
Start (High)
1, 50000000 / (Frame Rate) * 10
}

from what I understand these lines are driving an internal signal that will set the time of exposure and the frame rate. now why 2 lines? could the value
s be wrong? thanks for helping.