Grc file for transmitter and receiver

i want to send andreceivevia the two ports i have in my USRPN210 using
XCVR2450 daughter board (half duplex). the ports are RF1, RF2. so if i
made in same grc file the transmitter andreceiveri don’t know which port
transmit and whichreceive. any one advise me to manage transmitting
receiving problem, how to check if the transmitting signal is work fine
as i saw it aftermodulationblock and before the sink?. and thanks