DS18B20 arduino error

Other Hardware Sensors
1

Hey i am using a DS18B20 sensor connected to a data board and arduino i already mounted the bord so it can read two sensors the value of the sensor is correct however the second one gives the folowing value :
Temperature 2 is: 27.37-196.60,-196.60
This is my code is there any mistakes ?? please help :[/b]

#include <OneWire.h>
#include <DallasTemperature.h>

#define ONE_WIRE_BUS 3
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
DeviceAddress tank_sensor = { 0x28, 0x95, 0xD2, 0xCE, 0x03, 0x00, 0x00, 0x51 };
//DeviceAddress digest_sensor = { 0x28, 0xD4, 0xD3, 0xCE, 0x03, 0x00, 0x00, 0xDE };
//DeviceAddress tank_sensor = { 0x28, 0x04, 0xCC, 0xCE, 0x03, 0x00, 0x00, 0x09 };
DeviceAddress digest_sensor = { 0x28, 0x0C, 0xFC, 0xCE, 0x03, 0x00, 0x00, 0x2C };

int pump_pin = 8;
boolean pump_on = false;
float tank_max_temp = 38;
float tank_min_temp = 35;
float digest_max_temp = 40;
float digest_min_temp = 30;

void setup() {
Serial.begin(9600);
Serial.println("Dallas Temperature IC Control Library Demo");
sensors.begin();

}
void print_temps(float tank_temp, float digest_temp) {
Serial.print(tank_temp);
Serial.print(",");
Serial.println(digest_temp);
}

void loop() {

sensors.requestTemperatures();
Serial.println("");
Serial.print("Temperature 1 is: ");
Serial.print(sensors.getTempCByIndex(0));
float tank_temp = sensors.getTempF(tank_sensor);
Serial.print("Temperature 2 is: ");
Serial.print(sensors.getTempCByIndex(1));
float digest_temp = sensors.getTempF(digest_sensor);
print_temps(tank_temp, digest_temp);
delay (1000);
}

2

First, you are assuming that tank_sensor is index zero. It isn't - digest sensor is index zero.
See this thread in which I explain how the sensors are enumerated by their ROM address and this thread in which I post a program which prints a list of ROM address in their bit-reversed order which shows how the Dallas library sees them.

Second, -196.6 Fahrenheit is -127C which indicates that either the sensor is not properly connected or you aren't using the library properly. My guess is that you are reading the temperature twice from the same sensor without requesting the temperature again.
I suggest that you request temperatures and read getTempCByIndex for both index 0 and 1. Then either do the conversion to Fahrenheit yourself - it's not difficult - or you can use the library function sensors.toFahrenheit which will do it for you.

Third, you managed to use bold tags, now read How to post code properly to see how to use code tags.

Pete

3

Dear Pete
Thank you so much for your return but can you be kind enough to elaborate your explenation i am new to this kind of programs and what you wrote seems quite difficult to me
Thank you so much !