getting a variable from a ds18b20

Projects Programming
1

Hello everybody.

i am new in programming and i am stuck with a project.
i want to control a relay and it is depending on a temperature,
so i use the 2 ds18b20 digital temperature sensors.
if one of the temperature sensors rise above the other the arduino must set the relay on.
the problem is that i dont know how to get a variable from the code i get from the arduino website:

https://create.arduino.cc/projecthub/everth-villamil-ruiz/temperature-sensor-ds18b20-3decfc

i hope somebody understand me and be able to help.

2

the problem is that i dont know how to get a variable from the code i get from the arduino website:

You can't. What you CAN do is get a value and store that value in a variable.

   int temp = sensors.getTempCByIndex(0);
   if(temp >= HotterThanHell)
   {
      TurnTheBlastedACOn();
   }
3

thanks a lot pauls i am much further now.
another question how do i get 2 values from both temp. sensors

4

i think i got it, not tested yet
if you see any faults please notify

thanks a lot for the help

temp_sens2.ino (1.18 KB)

5 
//Include libraries
#include <OneWire.h>
#include <DallasTemperature.h>

// Data wire is plugged into pin 2 on the Arduino
#define ONE_WIRE_BUS 2
// Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);
// Pass our oneWire reference to Dallas Temperature. 
DallasTemperature sensors(&oneWire);
int temp1 = sensors.getTempCByIndex(0);
int temp2 = sensors.getTempCByIndex(1);
int relaypin = 3;

void setup(void)
{
  Serial.begin(9600); //Begin serial communication
  Serial.println("Arduino Digital Temperature // Serial Monitor Version"); //Print a message
  sensors.begin();
  pinMode (relaypin, OUTPUT);
}

void loop(void)
{ 
  // Send the command to get temperatures
  sensors.requestTemperatures();  
  Serial.print("Temperature1 is: ");
  Serial.println(sensors.getTempCByIndex(0)); // Why "byIndex"? You can have more than one IC on the same bus. 0 refers to the first IC on the wire
  Serial.print("Temperature2 is: ");
  Serial.println(sensors.getTempCByIndex(1));
   //Update value every 1 sec.
   
  if (temp1 > temp2) 
  {digitalWrite (relaypin, HIGH); }
  else { digitalWrite (relaypin, LOW);}
  delay(1000);
}
6 
int temp1 = sensors.getTempCByIndex(0);
int temp2 = sensors.getTempCByIndex(1);

This will NOT properly initialize these variables.

  if (temp1 > temp2)

You have not initialized these variables. You need to assign values to these variables, in loop(), AND print the values in the variables, NOT call the function for the 3rd and 4th time.