I am aquiring 4 channels on an m-series board, the samples are hardware timed using an optical encoder. Because the shaft to which the encoder is attached spins at differnt speeds the actual sampling rate changes.
I was under the impression that the sampling rate property on the sample clock in DAQmx should be set to the highest expected sample rate per channel; however, there have been problems when the shaft spins slowly and the actual sample rate is much slower than that specified in the DAQmx Sample Clock. The problems consist of the analog channels no longer being aquired or the values having an error of up to 20%. When the sampling rate on the DAQmx sample clock is reduced such that it is closer to the actual sample rate these problems go away. Any thoughts as to why this would occur?
Does the specified sampling rate of the DAQmx sample clock need to be within a certian range of the actual sampling rate?
Thanks in advance,
Nick
