----- Original Message ----- From: "Mark Willis" To: Sent: Saturday, October 21, 2000 3:01 AM Subject: [EE]: Ideas on a Wideish area Data network > In an industrial environment, and/or a home environment, has anyone had > a fair amount of experience with Dallas 1-wire and/or a similar setup, > over say 200 foot ranges using slow communications (1200 baud to 9600 > baud)? > > I'd like to use RG58 coax for power plus comms for one design, unsure if > it'll actually be practical for power plus data though; Thinking 9 to > 12V DC power for this one, just thought I'd throw the idea out and see > if anyone had used something like this. Lots of "hash" near the > machinery, the cable can be in conduit for longer runs (not that THAT > will save you!), it would just be really really convenient to have one > cable (Ethernet-style) for data plus power - Alternately could use > (cheap!) RJ11/RJ12 style cables, though they have resistance and noise > problems, or RJ45 Cat 5 cables, a little costly but do-able and still > with the problem of a noiceable resistance at each connection. (With > those, go for say 14VAC power and opto-isolated RS422; proven, works, > pricey at the PC end.) Just would like to go Coax if I can I've found coax to be quite unhelpful in noisy environments. Being unbalanced it just soaks up those lovely impulses over long runs unless you ground it at frequent intervals. You should certainly consider balancing the 1-wire with RS485/422 drivers or similar. Unless it's balanced you'll not get any benefit from UTP. One solution I have used with some success in the past is to use a Belden foil-screened-twin audio cable (e.g. #8723) and studio type XLR connectors (Useful tip, don't use the chassis connection on the plug, connect the screen to one of the pins and apply equipment ground to mating pin on the socket.) This is much cheaper than UTP and gives good results for moderate speed data (I've used it up to 300k). It'd probably start to lose effectiveness at higher rates though. > Absolute requirement to be able to unplug each node, so just hard-wiring > isn't an option; Could use a molex style connector, trying to use > something quicker and easier to "plumb", if practical... The Belden cable is thin and easy to run in and it strips easily. If you want *really* quick and easy to install then there are solid core versions suitable for use with Neutrik IDC type XLR connectors. How much power do you need? Dallas have a suggested circuit for deriving parasitic power in their 1-wire data sheets - or you could use a phantom power scheme using centre-tapped transformers at each end, feeding power between centre-tap and screen. Hope this helps. Andy. . -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.