listening to rs485 serial port on BL4S200

Hello,
 

 I am using BL4S200  for my control project. BL4S200 is a slave device. Other equipment uses Modbus RS485 to communicate BL4S200. Actually, everything is working, but the only thing is I need use loop to check serial port weather I receive any request, is it possible to use some internal interrupt to detect information received on serial port? so I can remove the fast loop to save some resource.
 

 Thanks