TIQY

Temperature is often harder to control and test then they should be. You can solve this problem by creating the temperature logger. This specific circuit uses a DS1820 microcontroller to read the temperate, and since it doesn’t need to be calibrated you can count on a quick project without the hassles or frustration of trying to find an accurate set of temperatures to calibrate it with.
The logger probes measure temperatures from –55°C to +125°C (–67°F to +257°F). No calibration required.

“A PIC Arbiter acts as interface between the Dallas temperature sensors and a logging PC. There are 8 terminations or single wire busses. Each of the 8 busses can support up to 8 sensors. As many sensors can be installed as required, limited to 64 maximum.I have called it an Arbiter as the controller negotiates with each probe on the single wire bus. Each individual Dallas temperature sensor unique serial number. Where a particular probe is in relation to its peers, or particular bus pin on the PIC is irrelevant. The Arbiter sends to the PC the unique serial number of the temperature probe and its temperature in a serial frame. The PIC Arbiter identifies sensors on each bus. Additional sensors can be plugged in at any time. Each device is polled every five seconds: its address and temperature data are sent via a RS232 serial link to the PC.�?

Source [via] [DS1820 Data Sheet]