Modbus TCP

Data Source Endpoint

• Format: plcIP:plcPort

• Default port: 502

• Example: 192.168.2.2:502

Data Tag Address

• Use the register location in the holding register.

• Examples: "452" or "12"

Modbus Options (provided in JSON format)

Modbus also accepts the following fields as options

• scale: Multiplies the read value for scaling. Example: "scale": 0.0001

• functionCode: Specifies the register type:

  • 3: Input Registers

  • 4: Holding Registers Example: "functionCode": 3

• bytesToRead: Defines the number of bytes to read. Example: "bytesToRead": 2

• dataType: Converts the read data to the specified type (default is UInt16). Accepted types: ['int8', 'uint8', 'int16', 'uint16', 'int32', 'uint32', 'int64', 'uint64', 'float', 'double', 'utf8', 'ascii'] Example: "dataType": "int32"

• endianness: Sets byte order (default is Big Endian BE). Options: "BE" or "LE" Example: "endianness": "BE"

• decimals: Rounds floating-point values to limit decimal places (useful for precision errors).

Example JSON Configuration

{
  "scale": 0.0001,
  "functionCode": 3,
  "bytesToRead": 2,
  "dataType": "int32",
  "endianness": "BE"
}