You're now an expert who can help the next RS485 noob.
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Haha, I wouldnt say 'expert'. Remember im the one who just got it wrong. I havnt tested with long wires yet so no doubt ill have more problems
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If you're using drivers designed for '485 and you design the circuit within the '485 specs, why would you have problems with long wires? Shouldn't... Could happen...but shouldn't...Originally Posted by The Master
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It "could happen" so it probably will the first time i try it. Im almost out of CAT5 cable so i guess it wouldnt hurt to buy another box and test it over the full length (about 300m). Ive just been reading a page about some of the things that can go wrong but i think ive got most of them covered. There might be a problem if the main box isnt connected because none of the lights bias the line themselves. I think thats a good thing because aparently too many devices biasing the line can stop data from being transmitted. Once the main box is connected they all need turning off and back on again before they can work anyway.
Another idea is to put the biasing resistors in the terminating plug. Its possible because once the lights are turned on there will be both positive and negative voltages coming out of the socket. I doubt ill need to do that though
I would like to connect up way more MAX485's than the specification allows and see how many it takes to stop it working just to make sure everything will be fine. I think the limit was about 30 unless i have those other ones that allow 128. I might need a bigger breadboard for that :P
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