> You
> could implement a ring from individual point to point RS-232
> connections,
> but that would require two UARTs per node.
>
Not usually.  You only need two UARTS if you want a bidirectional ring.
Many sensors are wired as a RS-232 ring with one UART.  The receiver
listens to the left, and the transmitter talks to the right.

Sherpa Doug

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