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Thermocouple measurement

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I am using the PXIe 8821 for the DAQ application to measure the temperature from thermocouples. The thermocouples (Analog inputs) are connected to an amplifier that sends 0-10v analog signals. I managed to read the corresponding voltage of each thermocouple using DAQmx pallet, But now I want to convert it into temperatures. I have a prescaled voltage-temp conversion table, but I don't know how can I insert/use this table in LabVIEW to scale those corresponding voltages. what tools can be used?

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Message 1 of 8
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Hi Suhaib,

 

look for the Interpolate1DArray or Threshold1DArray functions.

Both can be used for LUT-(LookUp Table) based conversions…

Best regards,
GerdW


using LV2020 on Win8.1+cRIO
Message 2 of 8
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hi, thanks for your response.

I got the concept, but I am having a hard time applying it at LabVIEW.

can you give me an example, please?

Best wishes

Suhaib Al Sulaimani

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Solution
Accepted by topic author Suhaib@961

Hi Suhaib,

 


Suhaib@961 wrote:

I got the concept, but I am having a hard time applying it at LabVIEW.

can you give me an example, please?

Sure I can:

check.png

You provide your LUT as an array of points (each point is a cluster of X and Y value). Then Interpolate1DArray interpolates between your points…

Best regards,
GerdW


using LV2020 on Win8.1+cRIO
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Thank you, it worked well.

I kept the array as a control so in the future calibration these prescaled values are editable.

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Hi Suhaib,

 


Suhaib@961 wrote:

I kept the array as a control so in the future calibration these prescaled values are editable.


I usually keep those values in a CSV file, editable using Excel or any similar sheet-based tool…

Best regards,
GerdW


using LV2020 on Win8.1+cRIO
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Hi,

I totally agree that the solution I made was not practical. Although I tried to include the CSV file I faced one problem.

The file produces 2D array and later in my program, I need to interpolate in order to get an accurate value for the thermocouple readings. can you give me an example if possible?

The image shows how I did it first using the constant Array cluster.

I hope my explanation is clear

 

Thanks in Advance

 

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Message 7 of 8
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Hi Suhaib,

 

there is a nice function to convert arrays into an array of clusters:

check.png

Best regards,
GerdW


using LV2020 on Win8.1+cRIO
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