USRP2 to toggle beween Rx And Tx mode

Hi All,
How can i get a USRP2 to toggle between reception and transmission.I
need to receive data , analyse it ans thereafter transmit based on the
analysed data.While i have written the C++ block for this, i cannot
figure out a way to toggle between Tx and Rx modes on the fly.


Regards

Lt Col Udit Joshi
M Tech Student
Computer Science
IITD