Wow! This is getting serious, but I'm afraid I'm not sure I can be of much help
gskluzacek:
In the datasheet for the DS18B20 I haven't been able to find what maximum length the data line (wire) for the sensors can be as I would like to be able to put all my sensors on a single data line that would most likely exceed 500 feet. Would there be a need to some how boost or repeat the signal with a distance this large? If so, what would you suggest?
This is a completely different extreme for me. My remote is 500 miles but I just take the DS18B20 with the cable it comes with. In my case it is 5m! I have seen them 10m but I wouldn't be surprised if they don't get any longer, so you are right to ask the question.
Clearly there are two problems, power out and signal back, and, at 500 feet, I'm betting you will have at least one of them. A 5v supply at the remote point may fix both.
Are you powering the sensors with an external power source or are you in using them in "parasite mode"?
My sensors just get their power off the board. I have two at this stage and they simply plug into a (very) short prototyping shield.
I simply set it up according to this tutorial
Note that there is just one common pull-up resistor.
Can you post a Fritzing diagram to show how you have the temperature sensors wired to the Arduino?
I'm not sure that would help. It is a one-wire system and the tut. above says it all. I just did exactly what it said. What you really need to know about is stuff I don't know about, which are all to do with size and scale. If I was doing it, I imagine I would make up a separate distribution board with a single three core cable that plugs into one of my temp terminals.
You may find you are obliged to use a wireless link. There is a whole arena covering that. I'm not talking about WiFi, it's something else, but I don't know anything about it. It's called something like Zigbee and I believe it may work with the Teensy MCU, which talks Arduino.
On reflection, you may find this a more practical solution. Teensys are so cheap they are probably cheaper than the cable you are talking about!! And don't even talk about the stress incurred installing it - all 500 feet.....,