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Re: RE: Null Modem SLIP Connection

If you want to use RS-422, you can buy a RS-232 <=> RS-422 converter from companies like Jameco or Black Box.  You can probably learn more about it by finding a book on serial communications.  You'll be able to use RS-232 for your application without problem.  RS-422 is used for very long distance serial communications and multi-drop applications.  It handles noise well and does not suffer from the grounding problems that RS-232 has.  OK, one more thing.  RS-422 uses 4 wires; 2 for transmit and 2 for receive.  George mentioned differential transmission.  The first transmit wire, tx+ is referenced against the second, tx- rather than ground, this way any noise on the wires is pretty much cancelled out.  The same is true for the receive side.  If you have any more questions, I'd be glad to try to answer them

>>> "David Karlin" <funk48@travelin.com> 11/10/98 6:15:54 AM >>>
First of all, thanks for the extremely speedy response.

Secondly, the connection is for two machines in different rooms of
the same apartment.  (I'm loading up my new room-mates 'puter with
a second HDD for Debian.) The distance between the machines will be,
at most, 60-70 feet.

Thirdly, where can I find info on RS-422?

Thanks again,


> -----Original Message-----
> From: grep@calvin.captech.com [mailto:grep@calvin.captech.com]On Behalf
> Of George Bonser
> Sent: Tuesday, November 10, 1998 2:46 AM
> To: David Karlin
> Cc: Debian User
> Subject: Re: Null Modem SLIP Connection
> plip is less than serial, serial will shrink as speed increases, both
> depend on the quality of cable. DO NOT attempt a link betwen machines in
> different buildings or on completely different power circuits as the
> difference in ground potential may fry the serial ports. For long distance
> connections over cable, use a differential method such as RS-422.
> On Tue, 10 Nov 1998, David Karlin wrote:
> > Hello,
> > What is the practical limit for distance between two computers
> > connected via null-modem slip?
> >
> > How about plip?
> >
> > TIA
> >
> > --David
> >
> >
> > --
> > Unsubscribe?  mail -s unsubscribe
> debian-user-request@lists.debian.org < /dev/null
> >
> >
> >
> George Bonser
> The Linux "We're never going out of business" sale at an FTP site
> near you!

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