User`s guide

FUNCTIONS
SDK SECTION 11
Page 211
SetDMAParameters
unsigned int WINAPI SetDMAParameters(int MaxImagesPerDMA, float SecondsPerDMA)
Description
In order to facilitate high image readout rates the controller card may wait for multiple
images to be acquired before notifying the SDK that new data is available. Without this
facility, there is a chance that hardware interrupts may be lost as the operating system
does not have enough time to respond to each interrupt. The drawback to this is that you
will not get the data for an image until all images for that interrupt have been acquired.
There are 3 settings involved in determining how many images will be acquired for each
notification (DMA Interrupt) of the controller card and they are as follows:
1. The size of the DMA buffer gives an upper limit on the number of images that
can be stored within it and is usually set to the size of one full image when
installing the software. This will usually mean that if you acquire full frames there
will never be more than one image per DMA.
2. A second setting that is used is the maximum amount of time(SecondsPerDMA)
that should expire between interrupts. This can be used to give an indication of
the reponsiveness of the operating system to interrupts. Decreasing this value
will allow more interrupts per second and should only be done for faster pcs. The
default value is 0.03s (30ms), finding the optimal value for your pc can only be
done through experimentation.
3. The third setting is an overide to the number of images calculated using the
previous settings. If the number of images per dma is calculated to be greater
than MaxImagesPerDMA then it will be reduced to MaxImagesPerDMA. This can
be used to, for example, ensure that there is never more than 1 image per DMA
by setting MaxImagesPerDMA to 1. Setting MaxImagesPerDMA to zero removes
this limit. Care should be taken when modifying these parameters as missed
interrupts may prevent the acquisition from completing.
Parameters
int MaxImagesPerDMA: Override to the number of images per DMA if the calculated
value is higher than this. (Default=0, ie. no override)
float SecondsPerDMA: Minimum amount of time to elapse between interrrupts.
(Default=0.03s)
Return
unsigned int
DRV_SUCCESS
DRV_NOT_INITIALIZED
DRV_P1INVALID
DRV_P2INVALID
DMA Parameters setup successfully.
System not initialized.
MaxImagesPerDMA invalid
SecondsPerDMA invalid