Reference

Library

• Library Name: RS485_Wind_Direction_Transmitter_V2
• Download Link: GitHub Repository
• Installation: Extract the library ZIP file and copy it to your Arduino IDE’s libraries folder (usually located at Documents/Arduino/libraries). Restart the IDE to load the library.

Communication Protocol Description

• The default communication parameters are: baud rate 9600bps, one start bit, 8 data bits, no parity, and one stop bit.

• Modbus Register

• Modbus Register Parameter Instruction

Indication: the wind direction measured in degrees (°) from 0° to 360°

Example: If the returned value is 02 8F (hexadecimal) = 655 (decimal) ÷ 10 = 65.5°, the degree is the angle with the true north (i.e. 0°).

Indication: the wind value of 16 directions

Example: If the returned value is 00 04 (hexadecimal, true form), the high byte of the first byte is 00, the low byte of the second byte is 04, and the measured wind direction value is (00*256+04)=4, 0 for true north and clockwise 4 for true east.

Modbus address can be set to 0-255. You can use 0 address to set any address.

Example

1. Read the 360° wind direction angle (Modbus slave address 0x02)

   Host query frame (hexadecimal): 02 03 00 00 00 01 84 39 (8byt)

   Slave Add.	Function Code	Register Start Add.	Length of Register	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	2byt	2byt	1byt	1byt
   0×02	0x03	0x00 0x00	0x00 0x01	0x84	0x39

   Slave response frame (hexadecimal): 02 03 02 02 8F BC 80 (7byt)

   Slave Add.	Function Code	Number of Valid Bytes	Data Aera	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	1byt	2byt	1byt	1byt
   0×02	0x03	0x02	0x02 0x8F	0xBC	0x80

   Wind angle value = 02 8F (hex) = 655 (decimal) ÷ 10 = 65.5°, which is the angle with the true north (i.e. 0°).

2. Read the 16 wind directions (Modbus slave address 0x02)

   Host query frame (hexadecimal): 02 03 00 01 00 01 D5 F9（8byt）

   Slave Add.	Function Code	Register Start Add.	Length of Register	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	2byt	2byt	1byt	1byt
   0x02	0x03	0x00 0x01	0x00 0x01	0xD5	0xF9

   Slave response frame (hexadecimal): 02 03 02 00 03 BC 45 (7byt)

   Slave Add.	Function Code	Number of Valid Bytes	Data Aera	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	1byt	2byt	1byt	1byt
   0×02	0x03	0x02	0x00 0x03	0xBC	0x45

   16 directions value = 00 03 = 3, the direction is east-northeast according to the table below.

   Correspondence Table

   Direction	16 Directions Value	360°
   North	0	0° - 11.2°
   North-northeast	1	11.3° - 33.7°
   Northeast	2	33.8° - 56.2°
   East-northeast	3	56.3° - 78.7°
   East	4	78.8° - 101.2°
   East-southeast	5	101.3° - 123.7°
   Southeast	6	123.8° - 146.2°
   South-southeast	7	146.3° - 168.7°
   South	8	168.8° - 191.2°
   South-southwest	9	191.3° - 213.7°
   Southwest	10	213.8° - 236.2°
   West-southwest	11	236.3° - 258.7°
   West	12	258.8° - 281.2°
   West-northwest	13	281.3° - 303.7°
   Northwest	14	303.8° - 326.2°
   North-northwest	15	326.3° - 348.7°
   North	16	348.8° - 360°

3. Read device Modbus slave address

   You can query the devices at any address using 0x00 address (broadcast address).

   Host query frame (hexadecimal): 00 03 10 00 00 01 81 1B (8byt)

   Slave Add.	Function Code	Register Start Add.	Length of Register	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	2byt	2byt	1byt	1byt
   0x00	0x03	0x10 0x00	0x00 0x01	0x81	0x1B

   Slave response frame (hexadecimal): 00 03 02 00 15 8C D8 (7byt)

   Slave Add.	Function Code	Number of Valid Bytes	Data Aera	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	1byt	2byt	1byt	1byt
   0×00	0x03	0x02	0x00 0x15	0x8C	0xD8

   Current device Modbus slave address = 00 15 (hex), i.e. the current device Modbus slave address is 0x15.

4. Change register 0x1000, i.e. change Modbus slave address (ADDRESS)

   Change Modbus slave address to 03

   You can set the devices at any address using the 0x00 address (broadcast address).

   Host query frame (hexadecimal): 00 10 10 00 00 01 02 00 03 FA 00 (11byt)

   Slave Add.	Function Code	Register Start Add.	Length of Register	Number of Valid Bytes	Slave Add. to Be Written	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	2byt	2byt	1byt	2byt	1byt	1byt
   0x00	0x10	0x10 0x00	0x00 0x01	0x02	0x00 0x03	FA	00

   Slave response frame (hexadecimal): 00 10 10 00 00 01 04 D8 (7byt), and that indicates the modification is successful.

   Slave Add.	Function Code	Register Add.	Length of Register	High Bits of Check Code	Low Bits of Check Code
   1byt	1byt	2byt	2byt	1byt	1byt
   0x00	0x10	0x10 0x00	0x00 0x01	0x04	0xD8

Principle

The sensor uses a low-inertia wind vane to detect wind direction. When the wind changes direction, the vane’s tail wing rotates, driving an axle magnet through the shaft. A built-in hall sensor detects the magnet’s position and outputs digital wind direction data (360° angle or 16-point direction). The aluminum alloy shell and military-grade connector ensure durability in harsh outdoor environments.

Other Supplementary Information

1. Wire Color Definition:

   Color	Function
   Red	Positive (+)
   Black	Negative (-)
   Yellow	RS485+/A/T+
   Green	RS485-/B/T-

2. Installation Guidelines:
   The white dot on the sensor must face true north during installation to ensure accurate wind direction readings.

3. Dimension Diagram: