Re: linux and rs-485

From: Grant Edwards (grante_at_visi.com)
Date: 08/11/03 

Date: 11 Aug 2003 13:23:00 GMT

In article <3F374306.967659C8@lumino.de>, Michael Schnell wrote:

> A quite common (non-standard) modification is a "master/slave RS422
> Bus".

Yup. The places I've worked always referred to that as "4-wire
RS-485".

As opposed to RS-422 which was strictly a point-to-point
solution for two devices each of which had a driver that was
always enabled.

> Here a master sends to many slaves on one pair and all slaves
> send only to that master on another pair. As the slaves only
> send on request of the master bus release timing in not
> critical.

In fact, it's often best if the master never releases at all
and keeps its driver enabled all the time. 

-- 
Grant Edwards                   grante             Yow!  .. the HIGHWAY is
                                  at               made out of LIME JELLO and
                               visi.com            my HONDA is a barbequed
                                                   OYSTER! Yum!

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