Date: Mon, 16 Oct 2000 18:57:30 +0200 From: Martin Recktenwald <mreckt@nikocity.de> To: isdn@freebsd.org Subject: Re: error messages... Message-ID: <20001016185730.B267@nikocity.de> In-Reply-To: <Pine.BSF.4.21.0010152250530.539-100000@server.arg.sj.co.uk>; from arg@arg1.demon.co.uk on Sun, Oct 15, 2000 at 11:04:52PM %2B0100 References: <20001014101345.BD66F9B20@bert.kts.org> <Pine.BSF.4.21.0010152250530.539-100000@server.arg.sj.co.uk>
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On Sun, Oct 15, 2000 at 11:04:52PM +0100, Andrew Gordon wrote:
>
> I also note that AVM cards I've bought recently have had extremely long
> cords with them (about 6m long!): even with a correctly terminated bus,
> plugging one of these long cords into the middle may be enough to cause
> unacceptable reflections.
>
Only if there is something else wrong. 10m for connection cords is
allowed even in the worst case (~ 100m bus length), more might work
in many cases.
> > > I have been told that the NT can be switched into 'high power'
> > > mode to allow for longer cable runs
>
> It's not high power, it's a timing adjustment. But it only applies to the
> case of a single device at the end of a very long run (up to 800m); not
> for multiple devices. This is the switch labelled "S" and "L" (for
> "short" and "long") under the cover of the BT NTE8A. Should be in the
> "S" position for all normal uses.
>
This switch is probably for the "Extended passive bus" described in
A.2.1.2/ETS300012-1. It *does* allow multiple devices, but they
have to be grouped at the end of the bus, it looks like this:
|--+--+--+---------------------------NTBA|
TE TE TE
Martin.
--
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