Thermocouple reading

[Navarro_]

Hi,

I am working with a type K thermocouple and I use a LM 35 temperature sensor to get an accurate CJC. I have got an external serial device were I do the voltage measurement of both (K and LM35), that means I get the voltage value as string using VISA in Labview. 

I would like to use the thermocouple reading vi for the linearization. My questions are:

Which option should I choose on  the CJC sensor input of the thermocouple reading vi?

Can I connect the value that I get from the lm 35 to the CJC voltage input of the thermocouple vi?

Thanks

[MelanieE]

Hi Navarro,

could you please mention the exact name of the VI you want to use or add some code or screenshot, that shows the VI?

Thank you.

Best regards,

Melanie

[Navarro_]

Hi,

The VI name is Convert Thermocouple Reading.VI

I still don´t have any code, I just want to know how to use the VI or how could I linearize the Thermocouple measurement including the CJC temperature.

Thanks

[MelanieE]

Hi Navarro,

thank you for your answer.

The first thing you have to define, is the Temperature Unit you want to get as the output of the Converter VI. Please refer to the LabVIEW help for the options:

Convert Thermocouple Reading VI - LabVIEW 2014 Help - National Instruments
http://zone.ni.com/reference/en-XX/help/371361L-01/lvinstio/conv_thermcoup_read/

As you described, your serial device returns scalar singular values to you, choose the scalar option of the converter VI.

The CJC options depend on your reference sensor. You can use a voltage or current reference, depending on what signal comes from the reference. Please refer to the help and the following link for more information:

What is CJC and Why Does My Data Acquisition Board or Signal Conditioning Unit Include a CJC Sensor? - National Instruments
http://digital.ni.com/public.nsf/allkb/E332E1D829059FB5862570AE005066B3

I hope, this helps.

Best regards,

Melanie

[Navarro_]

Hello,

thank you for your answer. I still have a question about the Convert Thermocuople VI: What should I choose on the CJC sensor input, IC or thermistor?. My CJC reference is a scalar voltage from a LM35 (that I get as a string using VISA).

Thanks

[MelanieE]

The LM35 is an IC, so you should select IC here.

Best regards,

Melanie

[Navarro_]

Hello,

Ok, thank you very much. I will try it and I will tell you how its going.

Have a nice day.