Ethernet wires

jdolecki

I have a 12 conductor slip ring ( rotary coupling ) connecting my mother board on top of my robot to the bottom

of my robot were there and ethernet shield.

How many wires are used in ethernet communications? all 8 or less?

Thanks, john

schill

10BASE-T and 100BASE-T use 2 pairs (4 wires). 1000BASE-T uses all 4 pairs (8 wires).

http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair#Cabling

kwinn

If you are planning to use the slip rings for ethernet communications you may want to do some simple testing before committing a lot of time, money, and effort to it. There will be some impedance mismatch and noise problems to deal with.

jdolecki

I already have the slip ring on the robot. The parts list described it as a 4 power 8 communication type. But it is 20 years old. I metered out the connection and they seem to be working. Right now its wired to provide power to the top of my robot for the mother board. I use 4 wires each for power and ground because the DC_DC computer supply is rated at 250 watts and Im not sure of the conection quality I may change it to 2 or 3 wires but will have to get an amp reading whent the Mother board is running.

kwinn

That arrangement is fine for power, particularly unregulated (battery) input to the board. The filter capacitors on the regulators will take care of any noise caused by the slip ring contacts.

Nice looking chassis btw. What do you plan for it?

njineermikey1

Depends on whether you use power over ethernet or not.

Unpowered: Orang/white, Orange, Green/White, Green. Oranges and greens are swapped on a crossover cable.

POE: Same as above, except Blue/White + Blue = DC+, Brown/WQhite + Brown = DC-

localroger

10baseT, such as you get from a ENC28J60, is pretty forgiving. It only uses 2 pairs, and you can even run it considerable distance on cat3 (normal telephone wire) instead of cat5. Short unbalanced runs have never been a problem in my projects.

Phil Pilgrim (PhiPi)

If coupling noise from the slip rings turns out to be an issue, could you use WiFi instead?

-Phil

jdolecki

I was thinking wireless since i have 2 xbee's laying around and and arduino FIO board also. (And I cant get my Propeller Schmart board to work)

As for the robot im going to run Willow Garges ROS on it to roam around my house.

Follow my build on my Blog

http://assistiverobotics.blogspot.com/

erco

Cool syncro-drive bot. I saw one of these back in the 80's on a K2A robot by Cybermation in Roanoke VA. Please keep us updated with your progress! http://www.theoldrobots.com/Kludge.html

AFA your slip ring issue, could you live with a spiral wire connection that would allow you +/- N turns before it had to unwind? Your software could keep track of the position.

Edit: Just saw your blog... it IS a K2A. Where did you find it?

jdolecki

Edit: Just saw your blog... it IS a K2A. Where did you find it?

Ebay of course I been following it for a while and it hasent been selling. So when it got reposted at 750 I offered 550 and got it.

I got it for the base and drive system. The main pieces are cast aluminum The motors both work Freewheeling the motors draw anbout .9 amps so there does'nt appear to be any mechanical isues. The gearbox was leaking but I'm sure the seals are dried out so when the fabrication is done I will take it apart forpaint and cleanning and then replace any seals or bearings.


It came out of Purdue University. I got it at a thrift shop in Fort Wayne Indiana.