From owner-freebsd-isdn Thu Oct 19 17:40:57 2000 Delivered-To: freebsd-isdn@freebsd.org Received: from arg1.demon.co.uk (arg1.demon.co.uk [194.222.34.166]) by hub.freebsd.org (Postfix) with ESMTP id F17A837B4FE for ; Thu, 19 Oct 2000 17:40:54 -0700 (PDT) Received: by arg1.demon.co.uk (Postfix, from userid 300) id 636329B11; Fri, 20 Oct 2000 01:40:44 +0100 (BST) Received: from localhost (localhost [127.0.0.1]) by arg1.demon.co.uk (Postfix) with ESMTP id 5B33C5D05; Fri, 20 Oct 2000 01:40:44 +0100 (BST) Date: Fri, 20 Oct 2000 01:40:44 +0100 (BST) From: Andrew Gordon X-Sender: arg@server.arg.sj.co.uk To: Hellmuth Michaelis Cc: freebsd-isdn@freebsd.org Subject: Re: ISDN S0 bus wiring configurations In-Reply-To: <20001018064726.A7EFD3E8@hcswork.hcs.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-isdn@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Wed, 18 Oct 2000, Hellmuth Michaelis wrote: > >From the keyboard of Andrew Gordon: > > > > > > I have put up a text about ISDN S0 bus wiring configurations at > > > > > > http://www.freebsd-support.de/i4b/isdn-cabling.txt > > > > > > Corrections and additions welcome! > > > > It seems odd that you mention only 75R and 150R cable impedance, when most > > people probably use 100R cable (and termination is specified as 100R). > > This is how it can be read in I.430. As far as i understand it, every type > of cable has to be terminated with 100 Ohms but the maximum length varies > with the cable impedance. I read it as saying that the correct cable impedance is 100 Ohms, but allowance has to be made for people using wrong or poorly-characterized cables. Actually, I.430 doesn't seem to make any statement about what the bus cabling should be - neither characteristic impedance nor velocity factor are specified, yet both are relevant. BT's wiring instructions specify that cable to specification CW1750 should be used (this is similar to cat-5). BT and several other sources say that EN50098-1 is the definitive specification for S-bus wiring, but unfortunately I do not have a copy. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message