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#1 Mare

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Posted 08 October 2011 - 02:13 PM

I have two thermocouples.
First one is PT100 class B
Second one is calibration thermocouple from IFM

I made csv file for each thermocouple and got the results (look Attachments - Kalibracija.bmp).

Now I need to lineariate those two thernocouples and I do not know how.

Attached Files


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#2 Emil

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Posted 09 October 2011 - 10:05 AM

Hi Mare,
PT100 is not thermocouple - it's RTD. It uses totaly different principle ot convert temperature to electric signal.
What do you mean by "linearizing"?
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#3 Mare

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Posted 09 October 2011 - 10:59 AM

Hi Mare,
PT100 is not thermocouple - it's RTD. It uses totaly different principle ot convert temperature to electric signal.
What do you mean by "linearizing"?


Yes you're right,its RTD.
I have a module IO-PT400 and RTD. I put the RTD and calibration thermocouple from IFM in hot water and observe the difference in °C as you see in attachment file.
The blue line is RTD and the red line is IFM. Look first graph
Second graph is Razlika (difference) .

I'd like to make some linearization for RTD or correction :
If IFM shows 85,50 and the same time the RTD shows 85,1 I'd like to see in my display RTD=85,5 instead of 85,1.

In generally I'd like to calibrate my RTD to show real temperature.
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#4 Joe Tauser

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Posted 12 October 2011 - 06:24 AM

The best you can do is an approximation. Break your error into segments and create a data table in the PLC that has the average error for a given temperature range. Then use compare blocks on the reported temperature from the IO module to determine what range you're in, look up the error, and add or subtract it to create a corrected temperature value.

Joe T.
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#5 rayair

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Posted 09 November 2013 - 01:58 AM

I would like to know how to make ladder for pt100.
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