For this inquiry of yours may I know what device are you trying to connect with RUT955? Do you have the details for the Serial configuration part? What port is the device listening for the data communication part? Could you share with me more information on what are you trying to implement with RUT955.
You may refer to this link for more information about RS232/RS485 with RUT955: https://wiki.teltonika-networks.com/view/RUT955_RS232/RS485