RS485 Wind Vane Direction Sensor Always Return 0

I bought a DFRobot RS485 Wind Vane Direction Sensor, but the sensor is not working properly. When I try to read data through Modbus, it always returns 0. I tried your Arduino library as well as writing my own code, but I’m always getting 0 from the sensor. What should I do right now? Here is my code and the datasheet that you sent me. I supplied 12V to the sensor, and the connections are correct. 

// const uint8_t request_frame[] = { 0x02, 0x03, 0x00, 0x01, 0x00, 0x01 };

const uint8_t request_frame[] = { 0x02, 0x03, 0x00, 0x00, 0x00, 0x01 };

20:19:10.324 -> Wind Angle: 0

20:19:11.324 -> Request: 02 03 00 00 00 01 84 39

20:19:11.355 -> Response: 02 03 02 00 00 FC 44

20:19:12.329 -> Wind Angle: 0

20:19:13.326 -> Request: 02 03 00 00 00 01 84 39

20:19:13.359 -> Response: 02 03 02 00 00 FC 44

20:19:14.356 -> Wind Angle: 0

20:19:15.352 -> Request: 02 03 00 00 00 01 84 39

20:19:15.352 -> Response: 02 03 02 00 00 FC 44

20:19:16.348 -> Wind Angle: 0