What is rs232b?

Answer 1

The latest version of a very old standard for serial communication that was originally specified by the phone company for connecting a dumb CRT terminal (which the customer owned) to a 300 baud modem (which as it was connected directly to the phone line the phone company owned by law). It was never originally intended to operate at any speed faster than 1200 baud, as this was the fastest modem the phone company could connect to their lines back when RS-232 was first written. It was also never intended to be used to connect to devices other than terminals and modems, but people freely violate the standard to make other devices work with it.