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sensirion ek-h5 or Humidity Sensor SHT21 for labview


@ claudeuntel


thank you very much!


Works well with the Evaluation Kit EK-H5 and the SHT21 on LV2014 SP1

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Message 11 of 20

Sorry for the fast hype....

The Vi does not work with the SHT21.

Communication works but the conversion from the measured RH% and T values is not correct.

I did put in the conversion math from the SHT21 datasheet but it doesnt work either.


Probably the USB-dongle does need to recieve some other commands to work with the SHT21 but until now I couldnt figure it out.


Does anybody have another solution?

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Message 12 of 20

Can you put the vi you have NOW and perhaps some of us can see if we can fix it and share that with you...

I am not sure WHICH vi you are trying...

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Message 13 of 20

Hey davekorpi,


thanks for the fast reply!


I was trying to modify the llb shared before in this thread in order to work with the SHT21.

I tried to put in the valueconversion for the SHT21 (red) rather than the one for the SHT75 (blue) but as said, I only get weird numbers.

It is in the of the attached llb.


Funny thing is: when I use the conversion for the SHT75 I get the same wrong numbers as when I use the Sensirion USB-Software and tell it that a SHT75 is attached (as in: 10 degC lower Temperature readings, some % off RH readings).

But when I use the "right" conversions as in the attachment I get weird numbers way off something meaningful.


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Message 14 of 20

Your code looks fine!


I do not know why it does not work.


I had quite a difficult time getting any help from Sensirion.

Those guys at Code Warrior are helpful if you can get to them.


I will be looking into it more!


Just 10 Deg C off or really strange numbers!

Wonder if a bit is "shifted" one too many or something crazy like that!


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Message 15 of 20

for sht21 you need to write 2^14

(T=-46.85 + 175.72* rawT/(2*2*2*2*2*2*2*2*2*2*2*2*2*2)




Message 16 of 20

and for humidity 2^12

linRH=-6 + 125 * RHO/(2*2*2*2*2*2*2*2*2*2*2*2);

Message 17 of 20

Thanks a lot guys!

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Message 18 of 20

Does anybody know, how to read or write the "status register" of the SHT-75 sensor through EK-H5? I want to aquire data via LabView with measurement resolution of 12 bit (temperature) and 8 bit (hamidity) and on/off sensor's heating element.

Thank you very much!

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Message 19 of 20

Hello all,

I have 2 sensor SHT21+ 2 EK-H5. I want to put together into a GUI in LabView but I am beginer and I don't have ideea what I supposed to do. Can you help me with that?


I want to run both sensors in program... I saw a few post from you but i don't understood to much.


Really appreciate for you'r help!

Message 20 of 20