I have noticed that when adding DS1820s on separate wires to a single Arduino port, at some point they stop working, at about 20-25' of total wire length. All DS1820s work fine individually or when paired with any other device. Sometimes with long (16') wire the failure happens with 2 or 3 units. With shorter wire it's 3 or 4.
The question is, can I compile the one-wire code multiple times with a different port definition so that I can connect the sensors to multiple ports, thus reducing total wire length on each port?
The wire runs are long-ish because they are sensing the concrete temperature in a radiant heat floor and coming back to a common control panel. The 1/2" tubes for the sensors are already placed in the concrete, so wire length is set. I have noticed that the failure happens with shorter total wire length when I'm using a 4-wire, 22 gauge jacked cable and substantially longer total lengths when I use 24 gauge wire pair unjacketed telephone wire. So it's not wire length--I am assuming that it's total cable capacitance that's causing the problem.