Hi,
I'm using a U3-HV with LJTick-Resistnce to read 2 Pt100 as the attached scheme.
I use the formula:
R=(2.5-Vin)/Vin * 1000 ; to get Pt100 resistance
T=(R-100)/0.385 ; to get Temp. in °C
My problem is that Temperature fluctuates between 24 and 37°C. It seems to much for me.
What did I do wrong?
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So how much voltage fluctation are you seeing? We expect a count (~600uV) or so on low voltage analog inputs (FIO/EIO). Look at the "Resolution" section here:
https://labjack.com/support/datasheets/accessories/ljtick-resistance
The T4 is very similar to the U3-HV and you can see the math in this section results in a resolution of about 0.55 degC per count.