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.
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..
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).