Generally speaking, the maximum rate can be reached when there is only one channel. As the number of channels increases, the maximum sampling rate decreases correspondingly. But why can NI_6229 achieve the maximum sampling rate of 250KS/s for both single channel and multi-channel? What are its internal processing mechanisms?
there's just one ADC on this board, and it achieves a max sample rate of 250kHz.
This is valid for one channel, and also for multiple channels ("aggregate")…
I was in a another recent thread dealing with this term "sampling rate (aggregate)". I explained it by saying that it defined the maximum rate of A/D *conversions*.
What makes for some confusion is that DAQmx uses some different terminology and conventions. DAQmx doesn't give you access to individual conversions, it only gives you access to *samples*. Under DAQmx, 1 "sample" ALWAYS means 1 A/D conversion for each channel in the task. A task with 5 channels on a board with a 250 kHz max *aggregate* rate, would have a *sample rate* of 50 kHz.
When you read data using DAQmx, it will always be returned in units of samples which will include 1 A/D conversion for each channel in the task. You cannot retrieve only the A/D conversions for the 3rd channel out of 5.