>But certainly tens of thousands of bps are possible. I use 19.2 kbps
>with a "passivated" RS-232 network (every transmitter have a diode in
>series with the TX pin and the line is pulled down to -12V with a 3k3
>resistor) over 100m long.
>
>I have installed systems with up to six nodes distributed along the line.

I used to service a similar system, which could run at up to 38.4k, and have 
up to 31 terminals on it, using a similar 'passive RS232' with open 
collector drivers. 

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