tasmail/pyModbusTCP

A simple Modbus/TCP library for Python

pyModbusTCP

A simple Modbus/TCP client library for Python.

Since version 0.1.0, a server is also available for test purpose only (don't use in project).

pyModbusTCP is pure Python code without any extension or external module dependency.

Test

The module is currently test on Python 2.7, 3.4, 3.5, 3.6, 3.7, 3.8 and 3.9.

Status:

Setup

You can install this package from:

PyPI, the easy way:

sudo pip install pyModbusTCP

GitHub:

git clone https://github.com/sourceperl/pyModbusTCP.git
cd pyModbusTCP
sudo python setup.py install

GitHub with pip:

sudo pip install git+https://github.com/sourceperl/pyModbusTCP.git

Usage example

See examples/ for full scripts.

include (for all samples)

from pyModbusTCP.client import ModbusClient

module init (TCP always open)

# TCP auto connect on first modbus request
c = ModbusClient(host="localhost", port=502, unit_id=1, auto_open=True)

module init (TCP open/close for each request)

# TCP auto connect on modbus request, close after it
c = ModbusClient(host="127.0.0.1", auto_open=True, auto_close=True)

module init (with accessor functions)

c = ModbusClient()
c.host("localhost")
c.port(502)
c.unit_id(1)
# managing TCP sessions with call to c.open()/c.close()
c.open()

Read 2x 16 bits registers at modbus address 0 :

regs = c.read_holding_registers(0, 2)
if regs:
    print(regs)
else:
    print("read error")

Write value 44 and 55 to registers at modbus address 10 :

if c.write_multiple_registers(10, [44,55]):
    print("write ok")
else:
    print("write error")

Documentation

Documentation available online at http://pymodbustcp.readthedocs.io/.

Know issue

On windows OS with older Python version (<3), win_inet_pton module is require. This avoid exception "AttributeError: 'module' object has no attribute 'inet_pton'".

install win_inet_pton:

sudo pip install win_inet_pton

import win_inet_pton at beginning of your code:

import win_inet_pton
from pyModbusTCP.client import ModbusClient