I doubt that this level of control (includes fiddling with control signals like RTS (Request to Send), CLS (Clear to Send), etc is needed. I think all that is needed here is binary data send/receive (not low level access to the flow control signals).
in reply to Re^3: serial port hex only
in thread serial port hex only
A modern computer can keep up easily with the port, even at "high" baud rate settings.
Also many of the computers nowadays have very limited RS-232 support and all of the flow control signals may not be even available! xon/xoff flow control is the way to go (if possible and needed) - however even no flow control at all is often fine!
The serial port chip or emulator will have at least 16 bytes of buffer. If this is a simple request/response protocol (no asynchronous messages being used), the programming should be fairly straight-forward.
RS-232 serial port communication is going the way of the dodo bird although it will "live" and be useful for a very long time.