2/3/4-Wire RTD circuit PUBLIC

Thanks for your comments RogerFL. The 2-wire circuit you got it's right. Thanks for the correction, I'll make the change in my description. Now, let's take a look at your circuit. In case the RTD ohm value equals 580 you get a Vout of 583.35 mV which seems usable in the first sight. So, let me choose a value inside the RTD sensor range, e.g 100 ohm which is the resistance of the sensor at 0^oC. So, 100 ohm value for RTD yields a value of 103.5 mV for V_out. As long as we feed the sensor with 1 mA, we get 103.5 ohm for RTD instead of 100 ohm. If we take a look at a RTD resistance vs Temperature table, we'll see that instead of reading 0^oC we read 9^oC. This not acceptable for most applications (maybe all!). It's very common to measure temperature within a range of +/- 0.1
Well, some times +/- 1 or a little more is acceptable. It depends from the application. But 9 degrees is clearly not an option. In conclusion, is a 2-wire RTD sensor useless? Well, as long as you keep the sensor distance from the measuring device short enough, the answer is... no. Remember that the wire resistance is set at 1.71 ohm. This means, A LOT of wire. So, you can try to figure out which is the max wire length to get acceptable readings from your 2-wire RTD sensor.