There are schemes to use RS232 as a net -- using diodes to acheive the isolation.  I
don't have any specific links, sorry.
David

Larry McKibben wrote:

> Hi Folks,
>
> I'm a PIC newbie.  This is my first question to the PIC list.  I signed up and
> have been reading the list for about a month and a half.
>
> I want to use a 16F76 as a master for a burglar/fire home alarm system.  I want
> to have maybe 4 16F628's around the house for remote access.  Using the USART
> functionality, the 4 remote transmitters would be electrically be in parallel to
> the 16F76's receiver input.  The data sheet does not state the 16F628 USART/TX
> (RB2 - pin 8) as open drain.  Will paralleling them be a problem?
>

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