07-01-2013 06:49 AM
I have a chart of acquisition for Ni pci-6281M SERIE , my question is how to program low-pass filter and how to choose the frequency of sampling in mode continuous sampel, and cut's buffer in éxecution. I usethesoftwareLabVIEWsignalexpress
07-02-2013 11:30 AM
Hi 123M,
You may receive more guidance if you can provide some more detail of your application. What type of signal are you bringing into the 6281 card? Is this from a sensor? If so, what make/model/type of sensor?
As for adding filters in Signal Express, you should read the Signal Express Help file here.
Andy C.
Applications Engineering
National Instruments
07-03-2013 05:27 AM
Salut Andy-C et je vous remercier beaucoup. J’ai un capteur de contrôle non destructif à « courent de Foucault » qui une bobine qui a les caractéristiques suivantes :
nombre de spires =170
le rayon intérieur =2.35mm
le rayon extérieur =4.5mm
hauteur =2.2mm
Je veux acquérir avec la carte pci-6281 une tension et un courant pour un signal d’alimentation :
V=2V valeur efficace
f=100khz fréquence
Ma question est comment choisir le paramètres de cadencement (fréquence d’échantillonnage et la taille d’échantillon à lire) et comment mesurer le courant, logiciel utilisé LabVIEW signalexpress.
07-03-2013 05:33 AM
translate in english
Hi Andy-C and I thank you very much. I have a sensor for non-destructive control "eddy current" that a coil that has the following characteristics:
170 = number of turns
the inner radius = 2.35mm
the outer radius = 4.5mm
height = 2.2mm
I want to acquire with the pci-6281 voltage and current for a powersignal:
V = 2V rms
f = 100khz frequency
My question is how to choose the timing parameters (sampling rate and sample size to read) and how to measure the current. software used LabVIEW signalexpress .
07-04-2013 02:30 AM
For 100kHz use 500kSPS or the max samplerate
Sample length?....
Well, it depends a lot on what you want to measure. 100kHz sine: amplitude and phase? (
Distortion? Your max samplerate is 625kHz , hardly enougth to capture the 2. and 3. harmonic (300kHz migth be already cut by the aliasing filter)
How fast do you need the result? If you capture a long time your cycle rate is low.
I haven't done eddy current measurements, so my first try would be: capture 20 periodes, use single tone detection and record amplitude, phase* and the RMS of the residual.
*) that would involve that you can sync to your exitation signal