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Subject: RE: RS485 communication
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Chris Fowler <cfowler@outpostsentinel.com>,
       Robert White <rwhite@casabyte.com>, Ed Vance <EdV@macrolink.com>,
       "'Linux PPP'" <linuxppp@indiainfo.com>, linux-serial@vger.kernel.org,
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On Sat, 2003-03-15 at 12:46, David Woodhouse wrote:
> On Thu, 2003-03-13 at 23:30, Chris Fowler wrote:
> > Are you saying that for him to to use PPPD that he will have to write a
> > program that will run on a master and tell all the slave nodes when they
> > can transmit their data.  In this case it would be ppp data.  Hopfully
> > in block sizes that are at least the size of the MTU ppp is running.
> 
> You don't _need_ a master, although it's often an easy answer.
> 
> You can have a token-bus arrangement like ARCnet does. In fact, the
> ARCnet data sheets describing how it works may make interesting reading.

RS485 supports CDMA, thats more than enough to implement ppp nicely, all
you have to do is a little abuse in the app or driver layer to block
sending when carrier is asserted

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