Explanation of Modbus RTU Address Types

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Kinseal HMI as Master

The Modbus protocol uses different address types for specific read/write operations. These address types include 0x, 1x, 3x, 4x, 6x, 10x, 3x_Bit, 4x_Bit, and others. Below is a detailed explanation of each address type and the function codes they support.

Address Types and Function Codes:

  1. 0x (0-65535):
    • This is a read-write address type used to control the output points of a device.
    • Read Bit Status Function Code: 01H
    • Write Bit Status Function Code: 05H
    • Write Multiple Bit Registers Function Code: 0FH
  2. 1x (0-65535):
    • This is a read-only address type used to read the input points of a device.
    • Read Bit Status Function Code: 02H
  3. 4x (0-65535):
    • This is a read-write address type used to control the data registers of a device.
    • Read Data Function Code: 03H
    • Write Single Data Function Code: 06H
    • Write Multiple Data Function Code: 10H
  4. 3x (0-65535):
    • This is a read-only address type used to read the data registers of a device.
    • Read Data Function Code: 04H
  5. 3x_dw (0-65535):
    • This address type functions the same as 3x, with the difference being that 3x_dw reads double words.
    • If data is in the 32_bit unsigned format, the high and low bytes are reversed. For example, if 3x reads 0x1234, then 3x_dw would read 0x3412.
  6. 4x_dw (0-65535):
    • This is similar to 4x, but it reads double words.
    • For data in 32_bit unsigned format, the high and low bytes are swapped. If 4x reads 0x1234, then 4x_dw would read 0x3412.
  7. 3x_Bit (0-65535):
    • This is a read-only address type, similar to 3x, but it reads the state of a specific bit in the data.
    • Function Code: Same as 3x, but used for reading bit-level data.
  8. 4x_Bit (0-65535):
    • This is a read-write address type, similar to 4x, but it reads the state of a specific bit in the data.
    • Function Code: Same as 4x, but used for reading/writing bit-level data.
  9. 6x (0-65535):
    • This is a read-write address type used to control the data registers of a device.
    • Read Data Function Code: 03H
    • Write Single or Multiple Data Function Code: 06H
  10. 10x (0-65535):
    • This is a read-write address type used to control the data registers of a device.
    • Read Data Function Code: 03H
    • Write Single or Multiple Data Function Code: 10H

Kinseal HMI as Slave)

When the HMI is used as a Modbus RTU slave, specific address types correspond to certain function codes in the Modbus protocol.

Address Types and Corresponding Modbus RTU Function Codes:

  1. LB (HMI Bit Register 0-65535):
    • This corresponds to Modbus RTU addresses 0x and 1x.
    • Supported Modbus RTU Function Codes:
      • 01H (Read Coil)
      • 02H (Read Discrete Input)
      • 05H (Write Single Coil)
      • 0FH (Write Multiple Coils)
  2. LW (HMI Word Register 0-65535):
    • This corresponds to Modbus RTU addresses 4x, 4x_dw, and 4x_Bit.
    • Supported Modbus RTU Function Codes:
      • 03H (Read Holding Registers)
      • 06H (Write Single Register)
      • 10H (Write Multiple Registers)
  3. RWI (HMI Recipe Register 0-2999, Recipe Name 3000-3999):
    • This corresponds to the Modbus RTU address 3x.
    • Supported Modbus RTU Function Code:
      • 04H (Read Input Registers)

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