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From: jfh@killer.UUCP
Newsgroups: comp.org.decus
Subject: Re: Noisy terminal lines
Message-ID: <722@killer.UUCP>
Date: Wed, 1-Apr-87 16:47:14 EST
Article-I.D.: killer.722
Posted: Wed Apr  1 16:47:14 1987
Date-Received: Sat, 4-Apr-87 20:15:59 EST
References: <8811@decwrl.DEC.COM> <1592@tekigm2.TEK.COM> <1300@uwmacc.UUCP>
Distribution: na
Organization: The Unix(tm) Connection, Dallas, Texas
Lines: 25
Summary: Try terminating the RxD line with a resistor

[ Line eater at work - munch - munch ]

In article <1300@uwmacc.UUCP>, oyster@uwmacc.UUCP (Vicarious Oyster) writes:
> In article <1592@tekigm2.TEK.COM> jimb@tekigm2.UUCP (Jim Boland) writes:
> > >If there isn't any idle time,
> >>the problem is most likely a terminal line which is passing transmit
> >>data to receive data, using lots of CPU time echoing the same thing
> >>over and over. 
> ...
> >We traced it down to a noisy terminal line which had nothing connected at the
> >other end.  Disconnecting unused terminal lines solved the problem.

When I worked for Pinnacle Systems, we had a number of customers complaining of
the same problem - we had it real bad at our office because the serial cables
run in the ceiling over noisy stuff like light fixtures.  The best fix I
ever found was to tie the RxD line to ground with a 10K resistor.  If you
do this on the computer end of the cable, you don't have to disconnect the
unused (or switched off, like with a T-switch) cables.

- john.		(jfh@killer.UUCP)

John F. Haugh II
Ex Technical Support Analyst, Pinnacle Systems, Inc.

Disclaimer:	I don't work for Pinnacle anymore, much less speak for them.