Newsgroups: comp.dcom.lans.ethernet
Subject: Re: strange ethernet electric problem
References:  <[email protected]>   
[email protected] (Al Dykes) writes:

> In article ,
> Robert Redelmeier   wrote:
> >ghost in the machine  wrote in part:
> >> The cables work fine in my development enviroment. It is only
> >> in the industrial enviroment where the failure is detected
> >> and i suppose that it is related to the power line since
> >> my laptop connects fine when it is running on batteries.
> >
> >Two issues:  industrial environments are electomagnetically
> >noisier and any cable imperfections (like split pair) more
> >likely to fail.  In some environments STP is required.
> >
> >Second, have an electrician check out equipment grounding.
> >There may be a ground potential difference or ground noise.
> >
> >-- Robert
> >
> 
> 
> 
> Ethernet NICs isolate the computers at both ends from anything induced
> onto the cable by the RFI/EMI environment to something like 1000v.
> This would also isolate any voltage differences caused by grounding
> problems. 
> 
> RFI/EMI and ground-induced interference with properly-wired Ethernet
> equipment is effectively non-existent in the real world.

RFI/EMI and ground-induced interference with properly-wired Ethernet
equipment is effectively non-existent in the real world when you 
use unshielded Ethernet cable for thw wiring. 

When shielded cable (STP) is used then we have a system that can be 
sensitive to ground-induced interference. 


-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/