hmm,
It's a long time ago but I'll give it a try...

RS232 or it's ccitt V.24 equivalent is used as a signalling protocol between two serial devices. You will find it usually between a DCE (data communication equipment, ie modem) and a DTE (data terminating equipment ie PC or other serial terminal).

There are ways to use it as a multipoint protocol, but only if you agree on using half-duplex communication.This was commonly referred to as multidrop network. It needed special equipment to "tie" together the different links. One could use an analog device (line adapter), basically some kind of analog HUB equivalent or one could use a digital device (modem or port sharing device).

The way this worked was basically as follows:

central point was the master, and polled the remote stations. If a remote station was polled and had data to send to the central location, then it would raise RTS signal towards the modem. The modem would then send a carrier on the line and at the central point the MSD would detect the carrier and suppress possible transmissions from all other connected remote channels.
The remote site modem would, if sync was established between both modems, raise CTS towards the remote DTE.
The DTE could now transmit a data packet to the central site. If packet was sent, then remote site dropped RTS and the modem stopped sending it's carrier. The central MSD noticed the absence of carrier and enabled reception from all remote sites again. The central (master site) could then send a poll to the next remote station...

If the above doesn't make sense then let me know, I can explain further in a person-to-person email, as I suspect this subject can be categorized as off-topic


rgds
Patrick