As I understand it, RS-485 is purely hardware support. As for the software it depends what you really want to use the RS-485 link for. You can pretty much use it as a classical UART through ECOM-COMM, examples are available on GitHub [1][2]. If you want to use the more advanced capabilities of RS-485, you’ll need a protocol such as Modbus RTU [3].
As for the board itself the STM32F746G-DISCO, I’ll need to dive deeper into the BSP to know if some configuration is required to be activated to support the RS-485.
Thanks much for your sincere feedback here first of all, and could you please share with me also about the availability of the HDLC protocol implementation on top of RS-485?