Industrial Switch Cabling

This is a bit off subject, but does anyone know if there is a switch that supports shielded twisted pair cabling? We are networking some PLCs, and we found a switch, the Cisco Catalyst 1900 series switch, but in the specs, it states that it uses UTP, but in the factory/plant, we need shielded because of the noise. Any suggestions?

You can try Schneider Electric. http://www.modicon.com
I know their Connexium stuff uses shielded cables. I don't know who they are brand labeling but it might be Hirschmann.

Enlightenment Please

I was taught to only ground one side of a shielded cable, otherwise you would begin to create "ground loops". Someone who knows, Please clarify.

Hi,

It depends on the quality of the earthing. If your earth connection on both sides is the same you should ground your cable on both sides.
But if the quality of your earthing is not ok,(there is a difference in voltage) then you've got a small current going thru your cable. In this case you should ground your cable on one side.

Rudi

Guest,

I think the guys got off-subject on their replies. What you wanted is a way to switch a shielded cable signal on/off? I have used a common 2-contact control relay. Run the two signal wires to two N.O. relay contacts, and splice the shield back together, keeping your exposed unshielded wiring as short as possible. You can also add shielding around the relay (a metal box or wire mesh, but usually it is not necessary). It works great, is easy, simple, and cheap. I am sure that there are more exotic solutions, but I have never had the need to go any further than an off-the-shelf control relay.

I believe that guest was referring to an ethernet switch.

There a quite a few industrial switches out there. Din rail mountable and 24VDC powered.

http://www.google.com/search?sourceid=navclient&ie=UTF-8&oe=UTF-8&q=industrial+ethernet+switch

Well I think everybody is confused, I know I am.

UTP is Unshielded Twisted Pair.

My question is, does it matter? All the Shielded cable probably has is the tin foil stuff rapped around it. The switch won't care about that as long as it has a good connection between point A and B. Does the Spec say it has to be UTP, that it can't be sheilded?

I doubt guest will answer but I thought I would throw that out there for the rest of you.

In reality the switch doesn't care wether it gets UTP or STP cabling. However the other connected devices (i.e. PLC) might. This is the same issue as the shield conductor on RS232 cables.

Will using UTP create more noise or ground loops, hard to say. But, when you call for technical support and they ask if your cable is shielded the few (relatively) extra dollars a "shielded" switch costs becomes acceptable, after all if you haven't followed the instructions why do you expect them to help you.

Shielded twisted pair is less vulnerable for electrical and magnetically signals in it’s environment than Unshielded twisted pair.
Both cables are actually the same but by a shielded there is a small layer of foil around the wires. This should help against magnetically signals (should help.?..!?..).
A Switch doesn’t care what short of cable it gets. If only it can send it’s signals trough.
If you don’t want to have any noise, there is always fibreglass wires.. (a suggestion)