DM-aiomodbus

Asynchronous Modbus clients for Python with TCP and Serial connection support.

Links

• PyPI
• GitHub

Installation

Check if you have Python 3.8 or higher installed:

python3 --version

Install the package using pip:

pip install dm-aiomodbus

Usage

Windows Setup

import asyncio
import sys

if sys.platform == "win32":
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

Code Example

import asyncio
from dm_aiomodbus import (
   DMAioModbusSerialClient, DMAioModbusSerialClientConfig,
   DMAioModbusTcpClient, DMAioModbusTcpClientConfig,
   DMAioModbusInnerClient
)


async def main():
    # Initialize Serial client
    serial_modbus_client = DMAioModbusSerialClient(
        config=DMAioModbusSerialClientConfig(
            port="/dev/ttyUSB0",
            baudrate=9600,  # default value
            bytesize=8,  # default value
            stopbits=2,  # default value
            parity="N",  # default value
            disconnect_timeout_s=20,  # default value
            operation_timeout_ms=100,  # default value
            error_logging=False  # default value
        )
    )

    # Initialize TCP client
    tcp_modbus_client = DMAioModbusTcpClient(
        config=DMAioModbusTcpClientConfig(
            host="192.168.1.5",
            port=502,  # default value
            disconnect_timeout_s=20,  # default value
            operation_timeout_ms=100,  # default value
            error_logging=False  # default value
        )
    )

    # Read/write register(s)
    async def callback(client: DMAioModbusInnerClient):
        await client.write_register(256, 1)
        result = await client.read_holding_registers(256, count=3)
        print(result)

    # Execute callback
    await serial_modbus_client.execute(callback)
    # or
    await tcp_modbus_client.execute(callback)


if __name__ == "__main__":
    asyncio.run(main())

Note: All read/write methods should be called inside your callback function

Types

Serial Client Config

class DMAioModbusSerialClientConfig:
    port: str  # Serial port name. Example: "/dev/ttyS0" - Linux UART, "/dev/ttyUSB0" - linux USB, "COM1" - Windows USB
    baudrate: int = 9600  # Baudrate in bits per second
    bytesize: Literal[7, 8] = 8  # Number of data bits
    stopbits: Literal[1, 2] = 2  # Number of stop bits
    parity: Literal["N", "E", "O"] = "N"  # Parity mode. N - None, E - Even, O - Odd
    disconnect_timeout_s: int = 20  # Disconnect timeout in seconds
    operation_timeout_ms: int = 100  # Not recommended to set it lower than 100ms
    error_logging: bool = False  # Enable error logging

TCP Client Config

class DMAioModbusTcpClientConfig:
    host: str  # IP address of the device
    port: int = 502  # Port number
    disconnect_timeout_s: int = 20  # Disconnect timeout in seconds
    operation_timeout_ms: int = 100  # For remote TCP connections, it is recommended to set 200 or higher
    error_logging: bool = False  # Enable error logging

Read Response

class DMAioModbusReadResponse:
    data: list[int]  # List of values read from device
    error: str  # Error message if operation failed

Note: This class has to_dict() method that returns a dictionary

Warning: If the operation failed, the data field will be an empty list

Write Response

class DMAioModbusWriteResponse:
    status: bool  # Boolean indicating success or failure
    error: str  # Error message if operation failed

Note: This class has to_dict() method that returns a dictionary

Warning: The status is considered True, if the operation did not result in an error.

Inner Client Methods

Parameters Description

• address: Register address (single integer)
• count: Number of items to read (default: 1)
• value/values: Value(s) to write (single integer or list of integers)
• slave: Slave unit address (default: 1)

Set custom logger parameters

from dm_aiomodbus import DMAioModbusSerialClient
from dm_logger import FormatterConfig


# set up custom logger for all clients
DMAioModbusSerialClient.set_logger_params(
   {
      "name": "my_name",
      "formatter_config": FormatterConfig(
         show_datetime=False,
      )
   }
)

See more about DMLogger here