Hi,
I´m in pedantic mode because I just want to avoid that newbies get told the same old mistakes.
RS232 is not a protocol.
And I guess with RS432 you rather meant RS422. It´s not a protocol, too.
While RS232 is meant for two partners only (peer to peer), RS422 is prepared for multiple partners, it may be used as a bus, but it needs extra control signals/wires.
RS232, RS422, RS485 ... are interface definitions. They define the physical interface, the wiring and the signal levels, maybe even connectors.
A protocol describes (part of) the meaning of the data. Packet sizes, error correction, timing...
Example:
when two persons speak with each other:
* Physical interface: air, electrical wires (good old telephone), RF (cellular phones) .... often multiple physical interfaces are combined.
* Protocol: language, the meaning of the words, how they are sparated, error handling
Klaus