Hello Saurabh,
You can replace the SRB board that is connected to PC with a NCB board. You have the possibility to select on with port (RS232 or USB) to connect the NCB board to PC, from BeeKit, when you generate the project for SMAC, from Platform -> board_config.h -> Default SCI port: SCI1 = UART on RS232 Connector or
SCI2 = UART on USB Connector. Also, SMAC allow two SRBs to talk to the NCB at the same time, but you should write your own code for this.
Regards,
Adrian