Thermocouple readings don't change.....

Other Hardware Sensors
1

Hi all,
I am putting together a project, just trying to read thermocouple values.
I am using a K-type as well as a MAX6675 chip.
For now I just want to read the temps on the Serial Monitor, however the values stay at whatever the first value read was, so for example if I put the thermocouple into 160F water, then turn on the Arduino, I get a reading of 160. But then if I move the tmermocouple to a glass of iced water, it still reads 160, until I reset the Arduino, then it reads the new temp.
Can anyone pls tell me why this is happening?

I am currently using the ladyada library for the MAX6675.

// this example is public domain. enjoy!
// www.ladyada.net/learn/sensors/thermocouple

#include "MAX6675.h"

int thermoDO = 11;
int thermoCS = 10;
int thermoCLK = 12;
int ReadC = 0;
int ReadF = 0;

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
//int vccPin = 3;
//int gndPin = 2;
  
void setup() {
  Serial.begin(9600);
  // use Arduino pins 
 // pinMode(vccPin, OUTPUT); digitalWrite(vccPin, HIGH);
 // pinMode(gndPin, OUTPUT); digitalWrite(gndPin, LOW);
  
  Serial.println("MAX6675 test");
  // wait for MAX chip to stabilize
  delay(500);
}

void loop() {
  // basic readout test, just print the current temp
  
   Serial.print("C = "); 
   
   //Serial.println
   ReadC = (thermocouple.readCelsius());
   Serial.print ( ReadC );
   Serial.print("  ");
   Serial.print("F = ");
   ReadF = (thermocouple.readFarenheit());
   Serial.println( ReadF );
   // Serial.println(thermocouple.readFarenheit());
 
   delay(100);
}
2

You are using the LadyAda example but have commented out the code that applies power to the breakout board. How do you have the chip wired?

My guess is that the CS pin is not being manipulated properly so the chip takes one reading at power-up and then continues to shift out that same reading every time.

3

You should be able to read the change in millivolt output of the thermocouple using a good volt meter. This might be obvious but the thermocouple unless it is already sheilded should be protected from the water with a plastic bag or something. Good Luck.If you are getting a voltage change then you have a problem further downstream. I have not worked with the Ladyada board.