Thermocouple measurement

[Suhaib@961]

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?

[GerdW]

Hi Suhaib,

look for the Interpolate1DArray or Threshold1DArray functions.

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

[Suhaib@961]

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

[GerdW · Accepted solution]

Hi Suhaib,

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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:

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…

[Suhaib@961]

Thank you, it worked well.

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

[GerdW]

Hi Suhaib,

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Suhaib@961 wrote:

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

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

[Suhaib@961]

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

[GerdW]

Hi Suhaib,

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