Kobuki provides two different interfaces for communication with host(e.g. Netbook), USB and Serial port however both utilise the RS-232 serial communication mechanisms.
For the USB connection, Kobuki uses a USB to serial converter internally, FTDI's FT232R. By using this chip, kobuki and host can communicate over USB interface. This will ordinarily make the kobuki device appear on COMN, ttyUSBN where N represents the N'th such device to connect. Since this can be non-constant if you are connecting several devices, you can (in linux) apply a udev rule:
This will ensure that the kobuki will always show up on /dev/kobuki.