Path: utzoo!utgpu!watserv1!watmath!att!att!emory!wuarchive!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpl-opus!hpspdra!howeird
From: howeird@hpspdra.HP.COM (Howard Stateman)
Newsgroups: comp.dcom.lans
Subject: Re: RS232 cable
Message-ID: <12710010@hpspdra.HP.COM>
Date: 30 Oct 90 22:23:35 GMT
References: <2404@gould.doc.ic.ac.uk>
Organization: HP Intelligent Networks Operation
Lines: 17

epl@doc.ic.ac.uk (Edward Peter Lennon) writes:
>2-Where did I get the figure of 50 foot maximum distance for RS 232 communications from.
>maybe a special type of cable,or maybe the book is wrong.

You got that 50-foot rule from standard RS232 terminals specs, which
were supported by a set of chips which would drive a +5v signal down 50
feet of wire. In real life, 75 feet was acceptable. Later chips were
made to support 1000-feet connections, but technically these were RS423,
I believe. Someone please correct me if I have the number scrambled.

What resemblence, if any, these specs have to LAN cabling standards, is
left as an exercise for the reader.

Howard Stateman  
Systems Support Engineer  Telnet (415) 857-3817
Intelligent Networks Operation, Palo Alto 
howeird@hpspdra.spd.HP.COM