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Part Number: ADS124S08EVM

Hi Team,

I am connected 4-wire RTD (PT 100) to ADC EVAL Board and try read data from GUI application .But I am getting error data.

1. Configured gain as 1 ,PGA register value = 0x08.

2. Configured IDAC current as 1000uA  , IDCMAG register value = 0x07.

Kindly help me on this to read correct data.  

  • Hi Uma,

    Are you manually setting the registers for the ADC, or are you using the script shown in the image?

    Also, how do you have the RTD connected to the EVM?


  • Hi Bryan,

    yes , I am using the  script as shown in the above image.

    I am connected 4 -wire RTD to the respective ports of EVM  as below image.

    please let me know if you need further details.

  • Hi Uma,

    Since this is a ratiometric measurement - that is, you are using the voltage established across R68 and measured by REFP1/REFN1 - the voltage seen in the Analysis Engine does not necessarily apply. You could change the voltage in the analysis engine window (it would be approximately RREF*IDAC = 1kohm*1mA = 1V in your case).

    It would likely make more sense to look at codes instead of voltage in this case. If you multiply the codes by RREF / 2^23, this will give you the RTD resistance. At room temp, you should be around 100ohm. Let me know if this makes a difference.

    I would also make sure that your RTD is connected to the EVM inputs correctly. I know that I have used a 4-wire RTD that was not labeled, and it was not intuitive which wire was which. Just another thought.