Thank you for your replying.
I understood that SC16IS7xx can be reversible but no official sample code. I am still confused that how to treat register ID and slave ID. So, can I expect that the protocol of the driver software between host (UART) and slave (I2C) is the same as similar product like SC18IM704? If no, could you tell me how to connect and use SC16IS7xx? Thank you in advance.