does anyone know how to calculate the impedance using waveforms

[crossrulz]

Where is the actual reading of the data?

[studentproject]

when loaded correctly it shows here as 2 waveforms, like i said i didn't make the VI, its a sample from UltimaSerial so LabView would work properly with the device i'm using.

[studentproject]

I know how to do the calculations by hand and to put the values in myself into the math code. I need to find a way to automatically take the values from the waveforms and use those numbers for my calculations. I am not allowed to calculate anything by hand for this project. I am just showing a waveform using the sample vi and need to automatically take the values to put them into the calculations, I have not set up the code for the calculations yet, but I will be using a formula node in order to do so as I am only using a student evaluation version of the program.

[studentproject]

this is the file i'm using with an extract single tone function on the side. Is it possible to extract the values automatically using LabView? I had to use the sample vi from ultimaserial in order to get my data logger to work properly with the program

[studentproject]

When I hook up my Data Logger to my computer and run the waveform, Does LabView automatically take the values and do the calculations? If so How do I set this up?

[studentproject]

anyone know how to use labview to place the amplitude value of a waveform as an input value for a calculation? I am measuring voltage and current. so for R=V/I does anyone know how I could pull the Voltage and Current values from the wave, only need the amplitude (ie. 8Volts and 30milliamps), and place these values in my formula automatically?

[Stuart.Parkinson]

Doing the calculations with the waveforms is not a problem. The problem here seems to be getting the waveforms out of your datalogger in a form we can work with.

What datalogger are you using? What format does it output data in? How does it connect to your system? Have you read the user manual for it?

You seem to be using UltimaSerial software which seems to be essentially dlls for widows development (not labview drivers) to talk to some piece of unspecified hardware (maybe a DATAQ device?). The UltimaSerial software looks geared towards windows development but maybe not so useful for LabVIEW if you can read the datalogger direct.

Before you will get anywhere you need to understand and clearly state the task in hand. Something like:

I have a datalogger which connects to my pc via xxx

It outputs data as (serial?) data in the format xxx at a rate of xxx

I need to read this data from the xxx port on my pc 

I then need to convert the read data from xxx form to a LabVIEW waveform type so that I can use the LV analysis functions to get amplitude, phase, etc.

When you can fill in all the blanks above then you might get somewhere. Meanwhile, look at the basic LabVIEW tutorials - you will need that basic knowledge of LabVIEW too.

[jamiva]

In your situation, you can't calculate impedance in the time domain by simply dividing voltage by current (R=V/I). It’s not as simple as R = 8 V / 30 milliamps. Just think what your waveforms look like. Both waveforms (voltage & current) are probably sinusoidal and have zero crossings. In the time domain, every time the numerator goes to zero, R=0. If the denominator approaches zero you get R approaching +/-INFINITY. I can tell you that that is not the right answer for your simple RC circuit impedance.

Impedance is frequency dependent. If the stimulus to the RC circuit is CW, you can calculate this in the frequency domain as others have said. You can do an FFT on the waveform. I've never used it myself but the "Extract Single Tone" VI looks like it could also work. Once you have the data in the frequency domain, you can then divide (using complex arithmetic) the voltage by the current for each frequency. NOTE: do the calculations on the peaks of the spectrum and not the noise. That should give you the answer the professor is looking for. I don't think this method will work if the stimulus is not CW, i.e. step function, delta function, etc.