Fibre Vs STP Vs UTP

[Doug_Adam]

G'day,

I am currently working on a problem with some ethernet communications between some PLCs and Citect PCs.
The problem is what type of cable to use.
So far, we have used fibre optics extensively. This has excellent noise immunity but, it was set up using Cat5 PLC and PC ethernet cards (as well as Cat 5 Switches). We therefore have a large number of converters all over the place, and as I found out this morning, not all of them come back on line instantly in the event of a power outage.
In a past life, I used Shielded Twisted Pair cable for most of my ethernet networking, and that seemed fine. I was thinking of re-running STP cable in local areas to reduce the number of converters in the areas. Of couse this would be for runs less than 100m long. I would still be keeping some fiber, however.

This is the question, has anyone run into problems with using STP cable?

I was also thinking that in many cases I may be able to use simple UTP cables. Has anyone had any major experience of using UTP in an industrial environment?

All comments are welcome.

Thanks,

Doug

[Steve Etter]

Hi Doug,

While I don't have extensive experience with ethernet cabling, I have wired one production facitity with about 15 or so drops using a mixture of both UTP (Unshielded Twisted Pair) and fiber optic cable. I have never used STP (Shielded Twisted Pair) for ethernet. In my application, much of the UTP cable had to be routed through very "noisy" environments and we did not detect any noise problems. Now that is not to say they do not exist, just that we never recognized any.

The fiber was only used for very long runs and it too presented no problems.

Here is a link to a Bell Labs comparison of UTP and STP cable systems.

Steve