I am currently using a 6341 DAQ and trying to read a speed signal from an electric motor (5 vdc square wave) using the DAQ assistant express VI. I can read the correct frequency of the square wave, but periodically get a reading of a million or more for the frequency. Given the fact that the 6341 can only sample at 500 k Hz, i know that frequency cant be real. The signal on an external O-scope shows the signal to be fairly clean.
Does anyone know why i may be getting the high frequency readings? and at what voltage does the counter trigger at, when counting the voltage rise of each wave?
Thanks
Erik