qt - How can my 57.6 kbaud serial connection trasmit over 100 kbytes per second? -

i have arduino dumps serial data continuously, , qt application reads data on computer.

i use qserialport, , can count larger amount of bytes received qserialport::baudrate() indicates.

interestingly, if use serial-to-usb converter on external device, baudrate set on external device corresponds rate can read data in qt application. in mode, arduino sends data on usart serial-to-usb converter, , it's seen virtual com port on pc.

however, if use "native usb" port on arduino due, still detected virtual com port , can read qserialport without special settings, calling open() , read(). if check baudrate calling baudrate(), 57600. however, timing qtime , counting received bytes, measure higher data rate 57600 bits per second.

if use buffer of 20 bytes, can manage around 100 kbyte/sec, buffer of 180 bytes can receive @ 1.4 mbyte/sec.

i checked data correctly received (and it's not junk).

is qserialport::baudrate() broken, or did miss obvious?