Freeze and Frequency Analysis

[Gregory88]

Hey Alex,

I still have just a straight line. Its like my MEMS gets no data, but i made a test in the DAQmx and the hardware works fine. I added some screenshots. You have any idea? 😞

The error message is also strange because i setted everywhere the same rate(1kHz) and samples(100) like ago. Or did i missed it somewhere?

Thank you very much!

[Duffy2007]

Hello Gregory88,

disable the highlight mode

[Gregory88]

no change 😞 just a straight line at -5 volts!?!?!?

[Gregory88 · Accepted solution]

Alex... i think i know why.. is it because i have changed the DAQ card? last week i used the SCB 68a with a PCI card. Now its a USB 6001 from NI

[Gregory88]

Thank you very much for your help and your patience! It works Some last questions:

For understanding: 1. why makes the FFT in the first milliseconds always this one big peak?

2. the amplitude in the FFT is in Herz?

For the program:

3. could it also be possible to vary the waveform graph 2 and 3 from 10 seconds manualy into 15 or 20 seconds? e.g. through a rotary knob?

[Duffy2007]

Hello Gregory88,

1. This could be the dc part in your signal.

2. What are the Output Units of FFT-based VIs?

3. Attached

[Gregory88]

Hi Alex,

thank you it´s also a nice feature, it´s great thou, but i would like to scale the x-axis and maybe y-axis by a rotary knob.

Furthermore i tried to write the data from the "waveform 2" & "waveform fft2" into a excel chart to print and compare them. Attached my VI with Express tools does´nt work as expected 😕

[Duffy2007]

Hello Gregory88,

How Do I Programmatically Format the X-Axis of a LabVIEW Graph to Display Timestamps?

With this way you can set also the minimum and the maximum for each axis.

There is also a method export grap to excel

Daten von NI LabVIEW nach Microsoft Excel übertragen

Save to a series of files and use the true to generate a new one.

[Gregory88]

Hi Alex,

the scale with the x and y axis doesnt work, just the description changes the graph stays constant. 😕

An "extra" idea for my VI is to create sth like a RMS - all three voltage signals (x-y-z-axis from the analog sensor) could combine together and could be visual in an extra waveform. would be usefull that i dont have to switch between the 3 signals of the sensor and compare everyone after each measurement.

attached the VI

[Duffy2007]

Hello Gregory88,

like this

for the scaling the range maximum property can be used.