Recently i got a request from a client. He had designed a control system, and wanted to expand it from stand alone to some multipoint system. The present hardware has two serial ports.

I could add a converter, and write or adapt some 485 type bus systems. There is almost no time at all to do this, so I did do some headscratching in order to come up with a less time consuming solution.
I Guess that "I could add a converter" means that the current is RS-232.

Sometimes when 'converting the existing' going 422 is easier than going 485. This will give you a master to slave channel and a slave to master channel, no 'turning the bus' required.

Erik