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From: Fred Bloggs
User-Agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0
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Subject: Re: Little help required........
References: <email@example.com> <firstname.lastname@example.org> <3DAED542.email@example.com>
Date: Fri, 18 Oct 2002 13:00:20 GMT
NNTP-Posting-Date: Fri, 18 Oct 2002 06:00:20 PDT
Organization: EarthLink Inc. -- http://www.EarthLink.net
Jim Thompson wrote:
> Fred, Been drinking already this morning ?:-)
> Where did you dream up this "three-state" stuff?
> ...Jim Thompson
Okay- I checked what little of the now ANSI/TIA/EIA-RS232 I could find.
This thing is up to version F and has been extended to lower voltage and
512Kbps in succeeding standards. It is strictly a logical two-state
unless you want to read something into the "fail safe" paragraph which
specifies four failure conditions that require detection, and then it
does become a three-state in a way. I am interested in knowing why this
interface was ever bi-polar given that it's a two state and the receiver
threshold is allowed to float around inside a +/-3V window. Usually
bi-polar operation allowed for magnetic coupling to eliminate common
mode interference, but you can't do that with RS-232,or can you.
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