stm32 NUCLEO_H743ZI2 custom extension board ,master slave communication with uart(rs485 protocol)

[RasailiTilak]

i have STM32 NUCLEO_H743ZI2 custom board , uart5 with the 485 protocol(THVD1406DR IC used ),
hardware connection for 485 protocol.
A1 to A2
B1 to B2
i want to make the one board master and other board slaves to send and receive data between the boards.
i tried with the different library related modbus not worked,
How can i solve this problem?