Thermocouple type K displaying wrong readings

[Doha_h]

I am using a K type thermocouple and i had set it to read the temperature in degree Celsius but i get values in 1000s when i just try to measure the room temperature.

I have attached my VI, would appreciate your help.

Thankyou.

[deceased]

I cant open your VI as I have an earlier version of LabVIEW installed. What DAQ hardware and settings are you using?

It sounds like you might be seeing raw readings on a microvolt scale, or you have pre-scaled temperatures that are then being scaled again as if they were raw voltages.

[Doha_h]

can you further clarify please

[deceased]

Doha, 

My ideas were only guesses. I cannot open the VI on my machine.

I can take a look but you would need to save your VI for the 2015 version and re-upload it.

You can do this by clicking FILE>Save for previous version.

[GerdW]

Hi Doha,

why do you divide your readings by the "sample per hour" value?

Why do you use DAQAssistent at all?

Why do you need to place one FOR loop inside another FOR loop?

Do you get any errors when running your VI?

Which DAQ hardware do you use?

[RTSLVU]

I see no scaling being applied to the raw measurement, so what do you expect your reading to be?

Also what about Cold Junction Compensation? Is your DAQ device taking care of this?

[Doha_h]

Here it is

[Doha_h]

Hello GerdW,

I am trying to average the temperature readings per hour over a number of hours.

i use DAQ ASSISTANT because i don't know any other tool that i can use. 

I used a FOR loop inside another as this is what i felt was an appropriate method to generate the results. 

No i didnt get any errors while running my VI. In fact, I dont think the problem lies in my VI as I get the same error in readings in NI MAX. 

i use NI 9212 hardware.

Thanks 

[Doha_h]

Hello

Is it necessary to scale it ? i had set the unit to deg C and the range to 0 min and 100 max 

the CJC is bult in

Thanks 

[RTSLVU]

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@Doha_h wrote:

Hello

Is it necessary to scale it ? i had set the unit to deg C and the range to 0 min and 100 max 

the CJC is bult in

Thanks 

---

I have never used that DAQ so I had to ask...

Did you make this thermocouple yourself from TC wire or is it a manufactured one?

Either way one of the main causes of extremely high thermocouple readings is an open thermocouple or bad/intermittent connection. Right off the top of my head I want to say "K" type thermocouples measure around 15 ohms at room temperature, or if you have another device to test them with like a Fluke 80TK, I would do that to make sure you don't have a bad TC.