RS485 communication in Beagle Bone Black with comms Cape

hello, I am having an issue with RS485 communication in Beagle bone Black.

For RS485 communication, I am using beagle bone comm cape A2 board mounted to beagle bone blackboard which is connected to another sam c21 board.

Pins: dev/ttyS4, TE:gpio48, and baudrate:9600 are handled from the code . While running the code, data is not receiving. I am new to this and have no idea about the issue. please help to come out of this problem