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Saving Data at lower rate

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Hi ,

 

I am acquiring data through DAQ . The sample rate is 20k and sample to read is 2k. These setting satisfies my requirements. But the data that I save is huge since I intend to aquire it for hours. Hence I would appreciate if somone could tell me how to save data at lower rate i.e. without changing the "sample rate" or "sample to read". Moreover if i could set the saving frequency of data each time I start the aqusition.

Thanks in advance for help.

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Solution
Accepted by topic author neevedit

What does your data look like, is it rapidly fluctuating or is it relatively steady with occasional outliers or ? I ask because the answer might vary depending on what the data looks like. Simply "decimation" (saving every X sample) may work for some data, but then you may miss an important "event". Alternatively, if the data is relatively constant, with occasional outliers, then saving a sample whenever the data moves out of a setpoint (the new sample is X amount greater or smaller than the last "setpoint") and then setting the new setpoint to that value may work for other types.

Putnam
Certified LabVIEW Developer

Senior Test Engineer North Shore Technology, Inc.
Currently using LV 2012-LabVIEW 2018, RT8.5


LabVIEW Champion



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Dear Mr.

Thanks for the reply. I would like to tell you that I the data which we are acquiring is constant and we would like to acquire as of it. Moreover our system has huge hysterics(30-40 seconds). We would like to write data on disc at a certain pace for example 1 second,1/10 second and 1/100 seconds without altering the set sample rate on DAQ assistant . We are also doing sample compression hence events will not be lost. Furthermore I would like to put time stamps on these data. For this I have put "Set dynamic data attribute" VI , but it is not working.
I am attaching the VI once more with slight change.
You efforts are much appreciated.
Warm regards,

Nonevent

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I haven't used it, but most of the questions I see regarding logging large amounts of DAQmx data reccomend using TDMS to record data.

 

There are LabVIEW functions as well as plugins for Excel, OpenOffice and MATLAB for loading TDMS data.

 

TDMS Direct Integration in NI-DAQmx Logging

 

The NI TDMS File Format

 


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You could try this example as well. If you do not like TDMS just replace with the appropriate file operation vi's.

https://decibel.ni.com/content/docs/DOC-8962


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I have nearly 32 sensor from which I will acquire data and each sensor is independently calibrated. Hence I cannot use 'Producer/Consumer pattern' is not well suited. Moreover I tiresome to set sample rate every time I run the VI. Hence I am using DAQ Assistance. Is there any solution that can be adopted in this way i.e. according to my VI.

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