Semi Period Measurement with E-Series Board

[AirSea]

Hello,
I am trying to measure a signal that has both a varying period and varying duty cycle.  I am currently using an extension of your example VI entitled "Measure Buffered Semi-Period-Continuous.vi" with "Samples to Read" set to 2 and a few more calculations in the while loop.  My problem alies in triggering measurements with my particular multi-function daq board which is a PCI-MIO-16E-4 NI device.  While I can live with discarding the first measured value, I would like to know if the measured semi period is a high value (5 volts) or low value (0 volts).  I attempted to use Measurement I/O<<DAQmx<<DAQmx Trigger.vi but found out that it was not compatible with counter measurements for my particular hardware.  If there is some way that I can either (A) start on a rising or falling edge or (B) calculate the voltage of the incoming signal then this would help me greatly in differentiating between the two semi period measurements.  While some of the other examples take into account rising or starting edge startup, I have not been able to find an example off hand that functions as well as the "Measure Buffered Semi-Period-Continuous.vi" for signals with both varying period and duty cycle.  Any help in this matter would be greatly appreciated.
Thanks,
Nick

[Jeff_T.]

To implement what you are asking, you must be able to do one of two triggering events.  You must be able to 1) arm the counter on a digital edge or 2) trigger a digital/analog read when the counter begins its measurements (to determine if the line is high or low).  The counter chip on your board does not support triggering of any kind.  This means there is no way to arm the counter on a rising/falling edge thus you are unable to set the "active edge" of your semi-period measurement.  There is also no way to start a DAQmx Read off the counter because you would need the counter to trigger another task.   In short, I would recommend any National Instruments PCI-660x or PCI-62xx board for your application because they do support counter triggers.