how do I acquire point-by-point data

[Juan M]

I need to measure the output signal of a pressure transducer connected to the discharge of a positive displacement wind mill pump. This pressure will fluctuate within each pumping cycle. I am trying to develop a LabView VI that acquires this data on a real time basis. I have to analyze this data with FFT and I need to compare it (both graphically and numerically) with displacement, force and flow signals acquired for the same time period for the pump it self. I have been reading about point-by-point signal measurement but I'm not sure if that is a correct approach. I am new to LabView. I went through the User Manual and thought the Measurements manual.

I would really appreciate if someone could give me some advise on which is the correct way to do this (using array based or point-by-point based analysis), and guide me on topics as point-by-point data acquisition, and appropriate sampling rate for data acquisition.

Best regards from Bogotá, Colombia (South America)

Juan M

[Sean_C.]

Hello Juan,

For the analog input part of you application, I suggest a hardware timed continuous acquisition. With this method, you would read a set amount of points per iteration of your while loop. Within this while loop, you could perform any analysis that you needed. You should base the sample rate of the acquisition on the pressure signal's fluctuation rate. As a general rule, you should sample 10x faster than the highest frequency component of your signal to get a good shape.
You can also look at the shipping examples to see how to set up this type of task in LabVIEW. From LabVIEW, select Help >> Find Examples... Then in the Example Finder, browse to Hardware Input and Output >> DAQmx >> Analog Measurements.

Let me know if you have any further questions.

Regards,
Sean C.

[Ron@ld]

Juan,

I think the best way is to opt for semi-real time in this case.
I myself work at a firm which builds pumps and through the years I've been
working with labview I found out that it's a convenient way to acquire
signals in small steps (let's say fractions of seconds) and do the analysis
on it. Mail me (remove nospam) and maybe I can be of help to you.

Kind regards,

Ron@ld

bubbynospam@iname.com


"Juan M" <x@no.email> schreef in bericht news:199702@exchange.ni.com...
I need to measure the output signal of a pressure transducer connected to
the discharge of a positive displacement wind mill pump. This pressure will
fluctuate within each pumping cycle. I am trying to develop a LabView VI
that acquires this data on a real time basis. I have to analyze this data
with FFT and I need to compare it (both graphically and numerically) with
displacement, force and flow signals acquired for the same time period for
the pump it self. I have been reading about point-by-point signal
measurement but I'm not sure if that is a correct approach. I am new to
LabView. I went through the User Manual and thought the Measurements
manual.<br><br>I would really appreciate if someone could give me some
advise on which is the correct way to do this (using array based or
point-by-point based analysis), and guide me on topics as point-by-point
data acquisition, and appropriate sampling rate for data
acquisition.<br><br>Best regards from Bogotá, Colombia (South
America)<br><br>Juan M