I tried to send a break and a 0x55 char, but no communication with the RN2483 afterwards (verified with a scope)
@Batilan
Here you find the user guide of the pictail board:
http://ww1.microchip.com/downloads/en/DeviceDoc/50002366A.pdf
In order to communicate with the board on the pictail rx/tx lines the board must NOT be powered from USB. Otherwise the usb->serial converter on the pictail asserts the RX line (of the RN2483).