docs/85355: [patch] Error in the pin numbers of the described connector in the Handbook (serial).

[Gary W. Swearingen]

The following reply was made to PR docs/85355; it has been noted by GNATS.

From: garys at opusnet.com (Gary W. Swearingen)
To: jpeg at thilelli.net
Cc: "Yar Tikhiy" <yar at comp.chem.msu.su>, bug-followup at FreeBSD.org
Subject: Re: docs/85355: [patch] Error in the pin numbers of the described 
 connector in the Handbook (serial).
Date: Tue, 30 Aug 2005 08:01:44 -0700

 "Julien Gabel" <jpeg at thilelli.net> writes:
 
 > Ok.  Is it worth to mention a specialized book ("RS-232 Made Easy",
 > for example) or not?
 
 I first wrote "not".  Too few people could find the old book in time
 for their need.  But it does have the important benefit of giving
 readers some reason to select the alternate design and thus justify
 the added paragraph's existance and discourage it's removal.  See
 below.
 
 > Note: there are two versions of the patch.  One with a reference to
 > the "RS-232 Made Easy" reference book, one without it.
 
 The first two paragraphs look OK to me, as-is.  But what you copied
 into the last para from my informal comments could be improved.  For
 example, I was wrong to have "generic null-modem"; there is no such
 thing.  I'll also comment on the first two paras, for kicks.
 
 +	  <para>If you prefer making your own cables (for quality purpose for
 +	    example), you can construct a null-modem cable for use with terminals.
 
 I would omit the (...); else, use "(for quality purposes, for example)"
 or "(e.g., for quality purposes)").  On second though, I would change
 it to simply "You can [...] with many serial devices".
 
 +	    DB-25 connector.  A warning though: the standard also calls for a
 
 I would omit "A warning though:" or at least "though".
 
 +	    straight-through pin 1 to pin 1 <quote>protective ground</quote>
 
 IIRC, that should be "<emphasis>", or something like that, so it
 could, for example, be rendered into italics.
 
 
 For the record: If this gets overhauled later, it should get a 9-pin
 version, which is more common these days (and which doesn't even have
 a protective ground pin).  Also: The design(s) _could_ be presented
 once in terms of signal names (eg, SG), and then the association of
 signals with pins given for 25-pin and 9-pin connectors.
 
 
 +	  <para>If the proposed design seems to be the most popular, others tend
 +	  to prefer a generic null-modem design like that, except it has pins 4
 +	  and 5 going to pin 8 and vice versa.</para>
 
    <para>The proposed design seems to be the most popular. In one
    variation (explained in the book <emphasis>RS-232 Made
    Easy</emphasis>) the note doesn't apply and at each end pins 4 and
    5 connect only to each other and to pin 8 at the other end.</para>
 
 The few who want to look for the book can start with a WWW search.
 
 Maybe someone can double-check my "replacement explanation".
 The book's diagram is something like this:
 
   1 -- 1  (No need to mention further, IMO)
   7 -- 7
   2 -- 3
   3 -- 2
   4+5 -- 8
   8 -- 4+5
   6 -- 20
  20 -- 6