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problems converting resistance to temprature

Hi Torb,

 

I can't open your VI as I'm tied to LV2011 here so I guess you missed the inversion dots at the last CompoundMath node…

 


the example you gave me is one way to go, but i am not an expert in math, so it was not that logical for me to do it in that manner, since i had the formula already it would be easyer for me to just use that.


I just wired your formula using basic LabVIEW functions…

 

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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Message 11 of 19
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hi

 

you are of corse correct, i managed to miss that. 🙂

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Message 12 of 19
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For those keeping score the code with corrected inversions at the last compound math node (Good guess Gerd!) is:

!1.png

in a formula node it would look like thus

Convert RTD Reading (scaler).png

I still can't find a souce to support 3.9135e-3


"Should be" isn't "Is" -Jay
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Message 13 of 19
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"I still can't find a souce to support 3.9135e-3"

 

The pt-100 element we use is calibrated once a year, we get a calibration certificate with the correct constants for our sensor element.

Message 14 of 19
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Maybe it does not have enough precision for your application, but I had the same problem and I resolved it in a different way.

I used the tables defined in the norms to generate a look up table. I also prepared the VI to work with PT1000.

I attached the VI.

 

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Message 15 of 19
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Hi Jon,

 

tables are fine, but why so complicated?

  • You don't need to check limits within each iteration of the loop, you don't need a loop at all!
  • Why did you limit the temperature to integer values?

 

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 16 of 19
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Hi GerdW,

to be honest, your code seems much simpler and elegant... thank you.

I am trying to copy in a new VI and run it slowly just to learn how some subVIs work, because I have never used the interpolate 1D array VI for example. By the way, I can not find in the palette the sub VI previous to the interpolate. Please, could you tell me wich one is? I am not able to find it anywhere...:(

 

Trying to answer to your questions:

"You don't need to check limits within each iteration of the loop, you don't need a loop at all". - Absolutely. The check should be done only once. I liked your solution of finding the max and min using the array Max&Min function.

"Why did you limit the temperature to integer values?" - I did it in that way because in the table I found it was with integer temp values. To be honest, I didn't try to interpolate between the values because I did not know that this function exist.

 

Best regards,

Jon

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Message 17 of 19
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Hi Jon,

 

the function before the Interpolation creates an array of clusters from the input arrays. You find it in the cluster function palette...

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 18 of 19
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Perfect! Thank you very much.

I attached the VI, just if someone needs it (LV2016).

All the gratitude to GerdW.

 

Best regards

Jon

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Message 19 of 19
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