Usually the device manufacturer provides an
for interfacing the device with the
(read the documentation). Very often (for low speed devices) they provide a serial port emulator, that is you communicate with the device using standard
communication (again, check out your device documentation).
is the Operative System
it provides are not only the ones used for 'the windows'. Specifically serial communication (
included) functions are ready-to-use for console applications.
If you are using the
chip a chip then (assuming the corrensponding driver is installed on your PC) you use standard
RS232 API for communicating with it
(see for instance: "Using Communication Resources" at MSDN
]) on the PC side.
On the other side you typically have a, hopefully, a microcontroller with