• You've been granted Beta access to this site, allowing you to explore some of the new features while they're still under construction. More information can be found in the Beta forum.

temp=85 - power problem?


New Member

in my house the free space for cables is minimal, so 1wire cables are near power lines :-( and every cable is about 6-8 mt. long.

I use a twisted 1 pair with shield (shield not connected). But I get some temp=85.

I suppose it is a interference problem or low power problem.

What do you think if I:
Solution 1:
1. get a power injector ( http://www.hobby-boards.com/catalog/links/...20Schematic.pdf )
2. connect
pin 2 of a rj45 (see http://www.hobby-boards.com/catalog/howto_wiring_diagram.php ) to shield
3. connect shield to VD0 (the 3 pin of DS18S20)

So DS18S20 has the +5v power via cable shield.

Solution 2:
1. get a power injector
2. use an unshield 2 pair cable?

solution 3:
Same as solution2 but with non-twisted cable.

Thanks for your help


Active Member
You are correct that the temp = 85 can be either noise on the line or a power problem but I have seen it more from noise so that would get my vote.

and every cable is about 6-8 mt. long.
How do you have your network laid out? If you have a star network and are not using a hub then that could be your problem.

Normal unshielded CAT5 cable is the best thing to use. I have heard that shielded cable can cause too much capacitance and you don't want to use non-twisted wire because that will reduce the rejection of noise.