Reference

Communication Protocol Description

Modbus Protocol

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

• Modbus Register

  Parameter	Register Add	Function Type	Function No.	Parameter Range & Description	Default Value
  Wind Direction Value	0x0000	INT16 RO	0x03/reading	0-324	None
  Modbus Slave Address	0x1000	INT16 reading-and-writing	0x03/reading0x10/writing	0-255	2

• Modbus Register Parameter Instruction

  Wind Direction Value
  Parameter Range	0-324	Default Value: none
  Parameter Storage	None

  Meaning: wind direction measuring value

  Example: If the returned value is 00 25 (hexadecimal, original code) = 0x0025 = 37, then the wind speed measuring value is 37/10=3.7m/s

  Modbus Slave Add (ADDRESS)
  Parameter Range	0-255	Default Value: 2
  Parameter Storage	Save immediately

• Example

  1. Read register 0x0000, that is the measuring value of the wind direction

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

     Slave Add	Function Code	Register Start Add	Length of Register	High Bit of Check Code	Low Bit 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 00 25 3D 9F (7byt)

     Slave Add	Function Code	Number of Valid Bytes	Data Aera	High Bit of Check Code	Low Bit of Check Code
     1byt	1byt	1byt	2byt	1byt	1byt
     0×02	0x03	0x02	0x00 0x25	0x3D	0x9F

     The wind speed value is (hexadecimal, original code) 00 25 = 0x0025 = 37, then the wind speed measuring value is 37/10 = 3.7m/s

  2. Modify register 0x1000, which is the Modbus slave address (ADDRESS)
     Modify the Modbus slave address to 03
     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 Address Written-in	High Bit of Check Code	Low Bit 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), that is, the modification is successful. After setting, you need to re-power on and restart the transmitter to make this address take effect.

API Description

    /**
      @brief  initialize serial port
      @param  device Address of serial port，In Linux, it is the directory where the device is located.
      @return  Return 1 for initialization failure, and return 0 for initialization success
    */
    unsigned char Init(char *device);
    
    /**
      @brief  Modify address
      @param  Address1 For the current address, you can set any address with 0 address
      @param  Address2 The modified address.
      @return  A return value of 1 indicates success, and a return value of 0 indicates failure
    */
    unsigned char ModifyAddress(unsigned char Address1, unsigned char Address2);
    
    /**
      @brief  Read wind speed
      @param  Address The address where you want to read the data
      @return  The return value ≥0 indicates successful reading, the return value is wind speed, and the return value -1 indicates failed reading
    */
    float readWindSpeed(unsigned char Address);

Other Supplementary Information