[ On Wednesday, October 18, 100 at 06:59:39 (+0000), dribbling@thekeyboard.com wrote: ]
> Subject: XON/XOFF serial handshaking?
>
> Was pricing up some cabling last night and a question sprang
> to mind.  When hooking up a serial terminal to a NetBSD box,
> is it possible to configure the port to use X-On/X-Off style
> 'software handshaking'? This would enable me to use a 3 wire
> null-modem cable (less expensive per metre) rather than my
> usual 7 wire type.

Of course it is possible -- but you will anger all Emacs users who try
to use your terminals!  :-)

Remember you can usually get away with cat-3 cable for RS-232 so long as
your runs are in metal conduit and so long as you terminate with
shielded in-wall junction boxes and use only shielded cable from the
wall to the terminal.

Of course the heavier gauge wire you use the longer you can stretch
RS-232 distance limits, so unshielded cat-3 won't cut it at much over
100 feet, even in a metal conduit.  With good drivers and individually
shielded cable though you can expect to go as much as 200' at 19.2kbps.

I had 150' of shielded 4-twisted-pair 22-gauge wire running at 19.2kbps
for several years at home and I never noticed any problem (though of
course most of the time I was running the layers protocol on that wire
and IIRC it has minimal error correction capability similar to UUCP 'g'
protocol, though not as sophisticated).

I had a client who I installed serial terminals and printers in a truck
and autobody repair shop for, and I ran several sheilded RS-232 runs
with about 18-gauge well over 250' and ran the terminals and printers at
9600bps with no problem.  Of course I was always careful to cross AC
lines at right angles, etc.

-- 
							Greg A. Woods

+1 416 218-0098      VE3TCP      <gwoods@acm.org>      <robohack!woods>
Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>