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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
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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
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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
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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 IOWarrior_SHT75_GetTempHumid.vi of the attached llb.

 SHT21.JPG

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
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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
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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
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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
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Thanks a lot guys!

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Message 18 of 20
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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
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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
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