Reading from a pt100 converter

Other Hardware Sensors
1

Hello,

I need to read from a 2 wire pt100 temperature sensor, and for that I have bought the following pt100 converter (the pdf is in spanish, but if you check the las page, the connection instructions are clear, which I think is what matters):

http://www.guemisa.com/conver/noupdf/Termoflex-web.pdf

I ordered it configured as follows:

Output: 0 to 5V
Range: -10 to 150 ºC

And this is how I'm connecting it:

First wire of the pt100 in pin 1 of the converter (see last page of the pdf).
Second wire of the pt100 in pin2.
A wire from pin 2 to pin 3.

230VAC (I am in Spain) directly from the socket to pins 4 and 6.

And I am connecting output pin 7 to the arduino analog input pin. But I am getting readings which fluctuate among the complete meassurement range with no sense. I have also tried connecting the V- (pin 8 ) to the Arduino, but it doesn't work either.

What am I doing wrong?

Thank you very much in advance.

2

Hi JohnLincoln, thanks for your reply.

I had already tried that. But that way I only get a constant reading of 5V (that is, 1023 ).

Regards.

3

Ok, nevermind, I solved the problem. The configuration is exactly as JohnLincoln said. I tried with a different pt100 sensor which is working correctly in another industrial device, and it worked well for me also, so the problem was simply that my sensor was not working.
However, the reading I get in my Arduino is about 4ºC less than the one I get in the other device. I assume this is simply a calibration issue between the different devices, right? But 4ºC seems a bit excessive.... :astonished: