there is some difference between DS18B20 & DS1820, as far as I tried DS18B20, with 30M have to pullup till 470 ohm even with cat5. software...impact, well "tie-up" means cable-tie up , no metal contact, along with 415V@60A 3phase power cables 50m away. -------------------------------------------------- From: "Vasile Surducan" Sent: Monday, June 09, 2008 11:18 PM To: "Microcontroller discussion list - Public." Subject: Re: [PIC] DS1820 wire how long can it go ? > 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 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist