I brought this question up to the group I work with here at automationdirect, this is what came up:

-- the interference is caused by the elctro-mechanical contact of the shoes to the rings. (wear spots, oxide build-ups, conductive lubricants, material, etc)
  -- it was worse when it ran intermittently versus continuously
  -- 4-20 ma or 0-10 vdc analog was consistant when isolated from the plc
  -- thermocouples just didn't work very well at all.

This is all I could get for you.

Carl
 

What type of slip rings? Are they dedicated to the PLC?

What type of signal are you trying to move across the slip rings?

For modems to use with industrial AC power slip rings try Data-Linc Group at http://www.data-linc.com.
For dedicated communications and instrumentation grade slip rings try Meridian Labs at http://www.meridianlab.com.

slip ring: any
Data: tying in a pc/operator interface.
      The PLC will be on a rotating piece of equipment.

the only power I need to supply is to the PLC.

hi schick...

as i have mention to you on the other forum, i did use a slip ring to control the temperature of a rotating cut/seal roll of a packaging machine. we used an Allen Bradley analog board, controlling the temperature of 3 heaters via
3 thermocouple also rotating 360 degrees. temperature is being controlled on an operator interface.

the slip ring construction is made of mercury which is a liquid metal, so i don't see any reason of wear and tear not like its counterpart.

i guess what you are trying to install is an operator interface in a moving or rotating platform and the main PLC on a stationary electrical cabinet..

if that is the case you will need a power supply and the communication cable ....which i believe the slip ring i mentioned above can handle without problem....i used a 12 in and 12 out slip ring...there should be more than 12 wires available..

let me know if you need more information...i can make some calls and give you more information about the manufacturer..although i am not working there anymore i managed to make some friends so the info should be easy..

dydt

Schick:
    I have already written a reply to this thread in the Automation & Robotic Engineering forum - I believe the real answer here is a wireless Ethernet link, using the slip rings only for the power required for machine and PLC (and perhaps a hard-wired E-Stop).

I would have to agree with rockcontrolman. I know many people who have had great results with radio modems. (wireless ethernet)

Carl