Hello!
I'm currently trying to get an anemometer (wind measurement device) to operate with my interface and computer but right now, it's not going so well = (
First of all, the anemometer provides a square wave signal and the frequency is proportional to the windspeed according to --> windspeed = Hz*0.5 - 0.5
So, 1 Hz indicates that everything is OK (all though -- > Windspeed = 0 m/s ) and 0 Hz indicates fault. At a frequency of 5 Hz the corresponding windspeed is equal to 2 m/s.
I'm using a NI USB-6211 to measure to differential in voltage and can thereby "plot" the voltage as function of time in LabVIEW 8.2 (Prof. Development System).
But when I'm trying to use "Timing and Transition Measurements" to get frequency as a function of the time in a Waveform Chart, LabVIEW stops and report the error:
"Error - 20308 occured... The waveform did not cross the mid reference level enough times to perform this measurement"
How do I solve this? I understand that the problem can be related to the fact that the frequency isn't large enough and thereby one period of the square wave isn't completed in the time where it is measured. Since I'm a beginner in LabView I hoping to get some help from someone with more experience than me.
Greatful for every answer I get. I attach a vi-file where I simulate the signal (and a filtered one), similar to my real signal where it is possible to decrease the frequency until it reaches the treshhold and "crashes". I also attach a pdf document with the technical specifications for the anemometer if this can be to any help
Thanks
Regards
/Mattias
