- From: Nils Juergens <ju_at_isf.rwth-aachen.de>
- Date: Fri, 30 Apr 2004 11:07:02 +0200
On Thu, 29.04.04, Alex Fielding <afielding_at_adelphia.net> wrote: > rtdma_mod.o: 4, dt= 50528 nsec, poll= 30, get_buffer_contents= 30 > rtdma_mod.o: 5, dt= 50848 nsec, poll= 282, get_buffer_contents= 282 > rtdma_mod.o: 6, dt= 50272 nsec, poll= 278, get_buffer_contents= 278 > rtdma_mod.o: 7, dt= 49376 nsec, poll= 272, get_buffer_contents= 272 > rtdma_mod.o: 8, dt= 49152 nsec, poll= 72, get_buffer_contents= 72 > In about 411 microseconds, I count 934 samples which is weird because that > corresponds to about a 400nsec sample time, whereas the fastest sample time > of the ni_pcimio is 800nsec, what I set it up for in the DMA command. If I > increase the interrupt to 100 microseconds, the bursty nature of the data > remains there. What could be causing this? comedi_poll() returns the number of bytes, not the number of samples. If your DAC has 12 or 16 bits one sample is returned in _two_ bytes. cheers, Nils
Received on 2004-04-30Z08:07:02