An RS485 slave is just like an RS232 slave. The slave only responds to requests from the RS485 master. It should not transmit any packet without the prompt from the master.
The only additional work would be to enable the RS485 level translator to transmit mode using a GPIO pin, just before the slave sends out a packet in response to the master. You can use the existing UART User Module.
Thank you for your reply! I have already implemented it by using just a UART component.