On 8/3/07, cllow2020 wrote: > I intend to use DS1820 at an environment for mountain plantation area( > not green house, is open area). Where there are auto control of temp for > water cooling, lighting control at night-time and chemical water spray. > Challenge is the tempreture sensor have to tie-up with 60A AC power > cables which provide 5 units of motor each 5 hp and some lights. If "tie-up" means for you using the same cable for AC and sensor, it's about a wrong design and not a challenge. If it's something else please excuse my poor english. The DS18B20 is working without any active pullup in a 50m chain using CAT5 cable where data is twisted with GND in one pair and VCC is twisted with GND in the second pair.The twisted pair has lower capacitance than shielded cable, and is much better. Vasile -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist