async-modbus
Async ModBus python library
Decision gist · record as of 2026-08-14
Yes, with conditions. The package fills a genuine gap for async ModBus clients and has low install friction. However, it is marked Pre-Alpha, has not been released in 296 days, and carries an unclear GPLv3 license declaration. Use it for non-critical applications or internal tools; verify license compatibility and test thoroughly before production deployment.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.6 or later.
- The modbus_for_url() helper depends on connio, which relies on the asyncio event loop; other async frameworks require manual StreamReader/StreamWriter wrapping.
- Low install friction; pure Python wheel.
License · maintenance · safety
GNU General Public License v3 (unclear) — License treatment is unclear; the package declares GNU General Public License v3 but lacks SPDX confirmation. Verify compatibility with your project's licensing requirements before use.
last release 2025-10-22 (296 days) · last repo commit 2025-10-22 · 12 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 82,521 downloads/mo, #14,159 on PyPI
Alternatives
Verify before relying
import asyncio
from async_modbus import modbus_for_url
async def main():
client = modbus_for_url("tcp://localhost:15020")
reply = await client.write_coils(slave_id=1, starting_address=1, values=[1, 0, 1, 1])
print(reply)
asyncio.run(main())- Whether the GPLv3 license is correctly declared and compatible with your use case
- Current stability and production readiness given Pre-Alpha development status
What it is and what it does
Async ModBus is a thin wrapper around umodbus that adds async/await support for ModBus client communication. It provides two main classes—AsyncTCPClient and AsyncRTUClient—plus a convenience modbus_for_url() function that accepts connection strings (tcp://, serial://, rfc2217://) and returns a ready-to-use client. The library is async-framework agnostic, working with asyncio, curio, trio, or anyio as long as you provide compatible StreamReader and StreamWriter objects.
The package depends on connio and umodbus. It optionally uses numpy arrays for efficient data handling when available. It supports reading and writing ModBus coils, discrete inputs, holding registers, and input registers across TCP and RTU transports, including remote serial connections via RFC2217.
Use it for
- Read and write ModBus coils and registers over TCP from an asyncio application using a URL-based connection string.
- Communicate with industrial devices over serial RTU using async/await without blocking the event loop.
- Bridge ModBus RTU over remote RFC2217 serial servers in an async context.
- Integrate ModBus communication into curio, trio, or anyio applications by wrapping raw socket streams.
- Efficiently handle bulk register reads/writes using numpy arrays for reduced memory and faster data manipulation.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, with conditions.
The package fills a genuine gap for async ModBus clients and has low install friction. However, it is marked Pre-Alpha, has not been released in 296 days, and carries an unclear GPLv3 license declaration. Use it for non-critical applications or internal tools; verify license compatibility and test thoroughly before production deployment.
Install
async-modbus on PyPI
Before you install
Low install friction; pure Python wheel. Maintenance status is aging—last release 296 days ago with modest repository activity (12 stars), though the repository remains active and not archived.
Requires Python 3.6 or later. The modbus_for_url() helper depends on connio, which relies on the asyncio event loop; other async frameworks require manual StreamReader/StreamWriter wrapping.
License in practice
License treatment is unclear; the package declares GNU General Public License v3 but lacks SPDX confirmation. Verify compatibility with your project's licensing requirements before use.
Quickstart
import asyncio
from async_modbus import modbus_for_url
async def main():
client = modbus_for_url("tcp://localhost:15020")
reply = await client.write_coils(slave_id=1, starting_address=1, values=[1, 0, 1, 1])
print(reply)
asyncio.run(main())Verify before relying
- Whether the GPLv3 license is correctly declared and compatible with your use case
- Current stability and production readiness given Pre-Alpha development status
Package facts
| License | GNU General Public License v3 unclear |
| Python support | Supports the current Python release >=3.6 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 2 packagesconnioumodbus |
| Maintenance | Aging 296 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 82,521 / month, #14,159 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 2 - Pre-AlphaIntended Audience :: DevelopersNatural Language :: EnglishProgramming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.6Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPython |
Evidence: async_modbus-0.2.3-py3-none-any.whl
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