Registry / http-networking / minimalmodbus

minimalmodbus

library2.1.1pypypi✓ verified 85d ago

Easy-to-use Modbus RTU and Modbus ASCII implementation for Python. Version 2.1.1 supports Python >=3.8. Released semi-regularly, with a focus on simplicity and reliability for talking to Modbus devices over serial ports.

http-networking database serialization

pip install minimalmodbus

github ↗package ↗docs ↗changelog ↗

INSTALL

IMPORT

SIG · MINIMALMODBUS

minimalmodbus

http-networkingpythonv2.1.1

Install

1.6s avg

Import

18ms

Disk

17MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v2.1.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.020s · 18.7MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.6s · import 0.016s · 19MB

17MB installed

● package 17MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Instrument

✓ from minimalmodbus import Instrument

✗ import minimalmodbus; inst = minimalmodbus.Instrument(...)

Wrong usage is uncommon but direct import is standard.

Quick example reading a Modbus register.

import minimalmodbus import serial instrument = minimalmodbus.Instrument('/dev/ttyUSB0', 1) # port, slave address instrument.serial.baudrate = 9600 instrument.serial.bytesize = 8 instrument.serial.parity = serial.PARITY_NONE instrument.serial.stopbits = 1 instrument.serial.timeout = 0.5 # Read temperature (register 0, signed 16-bit) temperature = instrument.read_register(0, 0, signed=True) print(temperature)

Debug

Known issues

breakingIn version 2.0.0, the 'minimalmodbus' module was restructured. The 'Instrument' class now requires explicit serial configuration. Old code using positional arguments for baudrate, parity etc. must be updated.

fix

Set serial parameters via the instrument.serial attribute after creation.

affects: >=2.0.0

gotchaModbus addresses are often 1-based in documentation but minimalmodbus uses 0-based register addresses. For example, holding register 40001 in Modbus maps to register address 0 in the library.

fix

Subtract 1 from usual Modbus addresses.

affects: all

gotchaThe library does not support Modbus TCP natively; it is serial-only. Users often try to pass a hostname and port, which fails.

fix

Use pymodbus for Modbus TCP, or use a serial-to-TCP converter.

affects: all

Errors

Common errors & fixes

ValueError: The slaveaddress 0 cannot be used.

Slave address must be between 1 and 247. Address 0 is reserved for broadcast.

fix

Use a slave address in range 1-247.

serial.serialutil.SerialException: [Errno 2] could not open port /dev/ttyUSB0: [Errno 2] No such file or directory: '/dev/ttyUSB0'

Serial port does not exist or is not accessible.

fix

Check the correct port name (e.g., /dev/ttyUSB0, COM3). On Linux, ensure user has dialout group permissions.

Upgrade

Version history

2.1.1latest on PyPI · released Jul 17, 2023

Audit

Dependencies

pyserialrequiredRequired for serial communication

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/pyhys/minimalmodbus ↗

packagehttps://pypi.org/project/minimalmodbus/ ↗

docshttps://minimalmodbus.readthedocs.io ↗

changeloghttps://github.com/pyhys/minimalmodbus/blob/master/HISTORY.rst ↗