Depending on the wincc SCADA configuration you simply need to select rs485 mode as either MODBUS gateway or over IP as a slave device. You can find more details in the following page: https://wiki.teltonika-networks.com/view/RUT955_RS485#RS485_Configuration.
I did that and nothing.
I also put a 116 ohm resistor between r + and r- in rut955 and in vain.
I also tried different settings as in the attached pictures.