marciokoko

Yes it does convert it to amps.  But the readings are off.  I thought it might have to do with the mapping function so I've tried modifying the ranges of it but I get varying values which don't seem consistent with reality.  For example : I always get 300 as the ABC value for room temperature.  And while tinkering with the temp range of the map function i can get the 300 to equal 25C.  But when I measure hot coffee for example, I get too small a change in temp, if I recall correctly something like 30C which in reality should be about 70C.  I've also measured with a digital thermometer side by side and even though I can get the starting  point 25c) to match between digital thermometer and the sensor, I can't get the other sample temperatures to coincide.

Thanks ive posted there already: https://forum.arduino.cc/index.php?topic=533442.0    

Im trying to use my PT100 with an Arduino-based PLC from Industrial Shields, which is basically an Arduino Mega encased in a plastic container. Im using a 250Ω resistor, actually 237Ω resistor between Analog and Ground.  Here is my setup: Here is my code: int sensorValue = 0; int temperature = 0; int ReceivedByte = 0; float f1 = 0; float t1 = 0; void setup() {   Serial.begin(9600);   Serial.println("hi..."); } void loop() {   delay(1000);   sensorValue = analogRead(A2);   Serial.println(sensorValue);   temperature=map(sensorValue,639,719,0,110);   f1 = temperature; // Float conversion   Serial.print(f1);   Serial.print("\n"); } These are my results for room temperature: I got the values from an online pt100 table for resistance and tabulated them from 0-110C in 10 deg increments and for the corresponding resistance using: nADC = 1023 * ( 237Ω/(237Ω+Rpt100)) Its not working because im getting values of ~300 for room temp which is well below this range, but since its not constrained (the map function).  What should I do? Thanks