Hi folks,
I use CAT5 cabling for my 1-wire projects, which allows 6 data lines with common ground and power.
The way I have been implementing this is Jack(1-6) are data lines, Jack7 is power and Jack8 is ground.
Before I start using other developers' boards and before I get too fixed on my schema,
I was wondering if there is a "standard" or at least accepted schema that we should be aware of.
Any thoughts?
Don't breath the magic smoke !
OK, so far I have not been able to determine any "standard" or de-facto standard for CAT5 cabling for 1-wire systems through researching many product links and general info.
That being the case, would it not be sensible for this community (and I'll include Pi bakers too) to work together to evolve something that allows compatibility between CAT5 connected devices?
I hope to hear some input on this topic before generating a wiring approach that may ultimately prove incompatible with other folks' projects. Do you have a CAT5 schema that you use? Then please post a reply here.
In my previous post I said that I use Jack(1-6) for data, 7 for power and 8 for ground on an RJ45 connector. Is that a valid starting point??
I think you're leading the field here.
Not sure how many users there are with six 1-wire connections in a project.
I have never used one myself.
In fact there is a quasi standard coping with a number of problems with such a 1-wire-network. It uses all 8 connections of the RJ-45 connector of a CAT5 cable including a secondary data line and a 12V power line.
1-Wire CAT5-cable use (colours by EIA/TIA-568A):
| Pin | Colour | Definition |
|---|---|---|
| 1 | white/green | 5V power ground |
| 2 | green | +5V (max. 50mA) |
| 3 | white/orange | secondary signal ground |
| 4 | blue | primary data line |
| 5 | white/blue | primary signal ground |
| 6 | orange | secondary data line |
| 7 | white/Brown | 12V unregulated supply (max. 200mA) |
| 8 | brown | 12V power ground |
BEWARE: not all manufacturers of 1-wire-sensors with RJ45 connector follow this quasi standard. Always consult the documentation of the sensor or you may destroy part of your network. By Maxim only part of these definitions are defined.
You should use an own power regulator in a sensor using the 12V line, because you get a voltage drop over the cable depending on cable length and used current (AWG 26=146Ω/1000m). In 100m distance with using 200mA of current the drop will already be 0,2A0.146Ω/m100m = 2.92V; so the 5V line will be reduced to 2.08V and the whole system won't work any longer. No more than about 300mA can be used on these lines!
Because on a RJ-12 connector (6P6C) the middle 6 pins are used, you will get Pin 2 to 7 of this definition, but remind that for connections over several meters there should be a sheilding. For RJ-14 (6P4C) you get pins 3 to 6 and will loose the power lines but may misuse the secondary data lines for power.