finding out the difference between 2 frequencies.

[frequency]

Im doing an online project where im in need of finding out the difference between the frequency of two signals.My point is like this, With one frequency a sine wave is generated and at the next step the sine wave is generated with a varying frequency(Only one signal is simulated at a time).I tried like this-For example, a signal of 30Hz is generated and i wrote the frequency value to a microsoft excel file(say file 1) then a signal of 300Hz is generated and that frequency is also written to a microsoft excelfile(say file 2).Then i tried to read both the values to find the difference between two frequencies.For which i used two Read LVM functions.Whenever the frequency changes the files corresponding to 30Hz writes the value in file1 and files for >30Hz(say 300Hz) also writes the value in file2.Now i get an Error4 while reading both.The values which i want to write and read are numeric integers.I used two write LVM and Read LVM functions. How can the difference between two frequencies be found out and displayed ?

[Norbert_B]

frequency,

first of all: you should do the analysis online? Why do you use files then?
On the other hand, no signal (even if periodic) doesn't reveal its frequency on its own. You have to do some kind of analysis on the data. Most often, FFT (fast fourier transformation) is used to transform the signal from the time-domain to the frequency-domain.
So maybe you should take a lookt into the basics of FFT.

Regarding error 4, i cannot say anything since i havent installed the easyio.llb... and when looking into your code, i am not sure where you think you are writing/reading excelfiles, at least i dont find any of your stated functions....

regrads,
Norbert B.