Dallas 1-Wire Problem/question

[mcbill20@xxxxxxxxx]

Hello all. I have an IOM142A board from phanderson.com that I have been
using for a couple of years now. I put temperature sensors in every
room of the house, as well as the garage and basement. Overall it works
pretty well except that I am getting a lot of read errors on certain
temperature sensors.

I have three wire runs. The first run is connected to the first input
on the IOM142A and has six sensors. It is a single line and ends in the
attic with a single temperature sensor on the very end of the line. The
second and third runs consist of a single sensor at the end of each and
are connected to the second output on the IOM142A. However, I was
forced to use a star configuration on these last two.

My problem is that the sensors on the end of each wire run have a lot
of read errors. Occasionally some middle sensor will log a lot of
errors, but generally they go weeks without a single error but the end
sensors log hundres of errors in that time (my software issues a read
every 15 minutes).

All the wire is CAT5E. The sensors are soldered to a three inch piece
of CAT5E which is crimped to a modular plug with gold contacts.  The
total length of the run with six sensors is less than 100 feet. The two
runs in the star configuration are approximately 15 feet and 35 feet
respectively.

It's strange to me that it's only the end sensors that have problems.
Should I be using some type of terminating resistor at the end of the
line? Any suggestions?

Thanks.
Bill