5 Sep
2002
5 Sep
'02
7:52 a.m.
From: "Gary Hildebrand"
<ghldbrd(a)ccp.com>
Eric Smith wrote:
NO!!!!
RS-422 inputs should not normally excede 7V. Many RS-232
are driven with 12 volts. Also, RS-422 is offset above ground
and not intended to take large swings below ground.
Most RS-422 receivers do not include ground as part of their
common mode operation, so you can't tie one input to ground
and get it to work.
Dwight
> <snip>
Connecting EIA-232 directly to EIA-422 could let the smoke
out of something, and we certainly wouldn't
want that.
ISTR that 422 was simply a balanced line version of 232. I think you
can just tie to the non-inverting line and ground and make it work.
Unless there's something else needed.
Gary Hildebrand
St. Joseph, MO
5 Sep
5 Sep
8:31 a.m.
Exactly, I just went through this exercise recently when I purchased a
couple of GPS frequency reference receivers. They had an RS-422 interface
with a DB-25 connector. In order to monitor its status or change some setup
data it required the use of a PC and software for that is available. But,
the PC has RS-232 with a DB-9. There are several companies out there that
make chips, or chip sets, to do the conversion from one to the other. Maxim
even sent me a couple of samples. Unfortunately they were in the SMD package
and the lead spacing was just too close for me to be able to use them. Then,
I found on ebay, a guy selling adapters from 422/232 and the reverse of
course. They look like the typical gender changers except these have a DB-9
on one end and an RJ-45 on the other. I bought 4 of them for less than $5
each, brand new in original boxes. Of course I had to take one apart, to
check it out, and it indeed did have several SMD ICs in it. The bottom line
is they work great. So, do not confuse the fact that you may think they are
similar. 422 by the way is specified to go almost 1000 feet, while with 232
you are lucky to get over 10 feet. Regards - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ, 07731
(732) 901-9193
----- Original Message -----
From: "Dwight K. Elvey" <dwightk.elvey(a)amd.com>
To: <cctalk(a)classiccmp.org>
Sent: Thursday, September 05, 2002 12:52 PM
Subject: Re: EIA 232 vs. 422, Color Computers (was Re: Serial floppy drives)
From:
"Gary Hildebrand" <ghldbrd(a)ccp.com>
Eric Smith wrote:
NO!!!!
RS-422 inputs should not normally excede 7V. Many RS-232
are driven with 12 volts. Also, RS-422 is offset above ground
and not intended to take large swings below ground.
Most RS-422 receivers do not include ground as part of their
common mode operation, so you can't tie one input to ground
and get it to work.
Dwight
> <snip>
Connecting EIA-232 directly to EIA-422 could let the smoke
out of something, and we certainly wouldn't
want that.
ISTR that 422 was simply a balanced line version of 232. I think you
can just tie to the non-inverting line and ground and make it work.
Unless there's something else needed.
Gary Hildebrand
St. Joseph, MO
11:41 a.m.
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12:23 p.m.
On Thu, 5 Sep 2002, Mike Feher wrote:
similar. 422 by the way is specified to go almost 1000
feet, while with 232
you are lucky to get over 10 feet. Regards - Mike
That's not true. Serial cable can go for a good many feet before the
signal breaks down (someone should pipe in with actual data ;)
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
12:43 p.m.
OK, I may be wrong, ( will not be the first time) I do have the original
Mil-STD or EIA specification on these interfaces, and admit that it is not
my specialty, however, it is fact, to the best of my recollection, that 422
will be reliable over a lot more distance than RS-232. I will dig out the
document, when I get a chance and quote actual specified numbers. Regards -
Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ, 07731
(732) 901-9193
----- Original Message -----
From: "Sellam Ismail" <foo(a)siconic.com>
To: <cctalk(a)classiccmp.org>
Sent: Thursday, September 05, 2002 9:24 AM
Subject: Re: EIA 232 vs. 422, Color Computers (was Re: Serial floppy drives)
Festival
On Thu, 5 Sep 2002, Mike Feher wrote:
> similar. 422 by the way is specified to go almost 1000 feet, while with
232
you are lucky
to get over 10 feet. Regards - Mike
That's not true. Serial cable can go for a good many feet before the
signal breaks down (someone should pipe in with actual data ;)
Sellam Ismail Vintage Computer
--------------------------------------------------------------------------
----
International Man of Intrigue and Danger
http://www.vintage.org
* Old computing resources for business and academia at
www.VintageTech.com *
4:31 p.m.
On Thu, 5 Sep 2002, Mike Feher wrote:
OK, I may be wrong, ( will not be the first time) I do
have the original
Mil-STD or EIA specification on these interfaces, and admit that it is
not my specialty, however, it is fact, to the best of my recollection,
that 422 will be reliable over a lot more distance than RS-232. I will
dig out the document, when I get a chance and quote actual specified
numbers. Regards - Mike
That I don't doubt. But I know for a fact that RS232 will work over
distances greater than just 10 feet as I've done it before and very
reliably :)
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
9:02 p.m.
New subject: more eBay stuff - not mine!
UK punters able to collect from the Lake District may be interested in a
MINC-11 that has so far not received any bids:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2049643025 I am tempted
... but its a long way away for me.
Andy
9:08 p.m.
New subject: also interesting on eBay
another item on UK eBay may also be extremely interesting ... if rather
expensive:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2051100106
is a BBC Domesday setup in (mostly) working order.
Andy
6 Sep
6 Sep
3:15 a.m.
----- Original Message -----
From: "Sellam Ismail"
That I don't doubt. But I know for a fact that
RS232 will work over
distances greater than just 10 feet as I've done it before and very
reliably :)
RS422 will work for 10x ~ 30x times longer cables of the same quality then
:-))
5 Sep
5 Sep
1:37 p.m.
> similar. 422 by the way is specified to go almost
1000 feet, while with 232
> you are lucky to get over 10 feet. Regards - Mike
On Thu, 5 Sep 2002, Sellam Ismail wrote:
That's not true. Serial cable can go for a good
many feet before the
signal breaks down (someone should pipe in with actual data ;)
It'll handle way more than its spec calls for. When researching the
content for "RS232 Solution", Joe Campbell ran it through a couple of
thousand feet of wire (on a spool). Well, I guess that by being on a
spool, the two ends were less than 10 feet apart. :-)
The original IBM PC Parallel Printer Port was the one that was spec'ed at
10 feet (3 meters). I often ran 30 feet with it.
I have no idea what the spec is for 1284.
2:29 p.m.
--- "Fred Cisin (XenoSoft)" <cisin(a)xenosoft.com> wrote:
Real world counter example:
VAX 11/750 in machine room with multiple Emulex CS/21 16-port serial
cards. Terminals in various offices strewn about a 3000 sq ft single-
story office/warehouse space. Telco 25-pair cables going from patch
panel in machine room, up to 18' high ceilings, along, then dropped
down into individual offices to provide 8 ports per office (Nevada
Western RJ-11 wiring system). Typical run - 150 feet from VT100 to VAX
over unshielded cable. Terminal speed - 9600 bps.
To wake the VMS terminal driver, one hit RETURN a couple of times. This
reliably produced one "u" echoed on the terminal per RETURN sent. Once
in use, no further ghosted characters appeared. Other than that,
the terminals were reliable. We even used the same wiring for Kermit
between machines in the machine room and at our desks (for those few of
us who had a development system in addition to the ubiquitous terminals).
So... 150-200 feet is OK for 9600 baud, but not entirely error free.
> similar.
422 by the way is specified to go almost 1000 feet, while
> with 232 you are lucky to get over 10 feet. Regards - Mike
On Thu, 5 Sep 2002, Sellam Ismail wrote:
> That's not true. Serial cable can go for a good many feet before the
> signal breaks down (someone should pipe in with actual data ;) It'll handle way more than its spec calls for.
When researching the
content for "RS232 Solution", Joe Campbell ran it through a couple of
thousand feet of wire (on a spool). Well, I guess that by being on a
spool, the two ends were less than 10 feet apart. :-)
Baud rate is part of the equation for transmission length with EIA-232.
The charts I've seen have a max length that tapers off at speeds over
1200 bps ISTR. The distance at 19200 bps is substantially lower than
even 2400 bps (50%?)
-ethan
P.S. - the cool part is that I have some of this stuff in my walls at
home - I have two 25-pair cables between the computer room and the
basement - one for phone, one for terminal sessions. It was nice
when I had multiple phone lines (fax/modem, home voice, home-office
voice). I'm down to one live voice pair out of 25, but the multiple
terminal lines are nice.
__________________________________________________
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Yahoo! Finance - Get real-time stock quotes
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6 Sep
6 Sep
9:01 a.m.
Hi,
Sellam Ismail <foo(a)siconic.com> said:
On Thu, 5 Sep 2002, Mike Feher wrote:
I've got a RS232 cable running 30 feet from down here to the upstairs
radio shack so I can have the PDP emulator upstairs and the terminal
down here. Works fine up to 57600 but won't do 115200. The terminal
only goes up to 19200 so that's ok.
--
Cheers,
Stan Barr stanb(a)dial.pipex.com
The future was never like this!
similar. 422 by the way is specified to go almost
1000 feet, while with 232
you are lucky to get over 10 feet. Regards - Mike
That's not true. Serial cable can go for a good many feet before the
signal breaks down (someone should pipe in with actual data ;)
7969
days inactive
7970
days old
11 comments
9 participants
participants (9)
-
andyh＠andyh-rayleigh.freeserve.co.uk -
ard＠p850ug1.demon.co.uk -
cisin＠xenosoft.com -
dwightk.elvey＠amd.com -
erd_6502＠yahoo.com -
foo＠siconic.com -
n4fs＠monmouth.com -
stanb＠dial.pipex.com -
voyager＠hol.gr