DS1820 1 wire and pic 16f877

I can read family code and ID number, but when I read temperature the result is to low. at room temperature I have -5 degree. I use parasite power. When I use third pin for power supply, I can t read nothing. I put 4,7 k resistor between data line and Vcc.

Post the code your using. I'm using the DS1820 and DS18B20 without issues using both parasite and non-parasite powered.