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Questions tagged [pymodbus]

Pymodbus is a python implementation of modbus protocol providing both client and slave features.

PYMODBUS is a full modbus implementation of modbus protocal using python. It provides both client and server features and supports Modbus over RTU, ASCII, TCP, UDP protocols. The library also supports both synchronous and asynchronous variants of both client and server features.

Pymodbus is supported on both on python 2.7 and python 3.x

For more info refer

203 questions
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What does the pymodbus "unit" parameter mean?

I have some modbus TCP code written under pymodbus 1.2 the relevent code was result = modbus_client.read_holding_registers(40093, 3) After updating to pymodbus 1.4.0 it wouldn't work until I cargo culted the new unit parameter into the function call…
Joshua Clayton
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Error in connecting 2 modbus slave pymodbus

I am working on pymodbus. Trying to read the data from multiple units (multiple slaves) it gives me data but when the 1 of the slaves did not respond or is off the other slaves also shows the error after some time. please help. Thank you from…
Eng
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pymodbus Exception Response(131, 3, IllegalAddress)

I'm trying to run this piece of code: from pymodbus.client.sync import ModbusSerialClient as ModbusClient import logging logging.basicConfig() log = logging.getLogger() log.setLevel(logging.DEBUG) client = ModbusClient(method='rtu', baudrate=9600,…
Dmitry Misharov
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Pymodbus RTU [Errno 25] Inappropriate ioctl for device

I'm trying to have a modbus RTU client on my Raspberry Pi 4 talking to the modbus synchronous server available in the pymodbus examples (https://pymodbus.readthedocs.io/en/latest/source/example/synchronous_client.html). I set up the server like…
Federico
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How to find out if a client is connected to a pymodbus tcp server

I have a pymodbus server running and I'd like to know if a client is connected to it that it is serving. Is there any way to do that? I can't see an obvious way. I'm using the synchronous server: pymodbus.server.sync.ModbusTcpServer
Mr. Fegur
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Pymodbus TCP `read_holding_registers` returns stale/old data

I've started using pymodbus to read values from modbus to store in a database off site. I've been struggling with an issue that the value received in the response is not the same as the value I can see on the Jace. I've tried modbus-tk as well and…
Pieter Hamman
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Modbus Error: [Input/Output] No Response received from the remote unit

I' trying to connect from my Mac laptop to a Modbus device (MR-SI4) using a serial connection using a USB RS485 converter that gets "mounted" to /dev/cu.SLAB_USBtoUART. This is my code: import logging logging.basicConfig() log =…
otmezger
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Modbus Python Schneider PM5300

I'm trying to get voltage or current from PM5300 meter, but always come 32768 only. The code: from pymodbus.constants import Endian from pymodbus.payload import BinaryPayloadDecoder from pymodbus.client.sync import ModbusSerialClient as…
Vinícius
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Unpack IEEE 754 Floating Point Number

I am reading two 16 bit registers from a tcp client using the pymodbus module. The two registers make up a 32 bit IEEE 754 encoded floating point number. Currently I have the 32 bit binary value of the registers shown in the code below.…
WK123
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modbus error failing to connect to ModbusTcpClient when reading/writing

Recently I have been tasked with a project involving reading Modbus data, specifically with the pymodbus package. before diving into this project I wanted to simulate some reading and writing of Modbus data (without having to use a machine) with…
Fastas
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How to update the value of pymodbus tcp server according to the message subscribed by zmq？

I am a newbie. My current project is when the current end decides to start the modbus service, I will create a process for the modbus service. Then the value is obtained in the parent process, through the ZeroMQ PUB/SUB to pass the value, I now want…
fish
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Cannot import BinaryPayloadBuilder from pymodbus

I tried to write this code below: from pymodbus.payload import BinaryPayloadBuilder But raises an error: ImportError: cannot import name 'BinaryPayloadBuilder' from 'pymodbus.payload' Need your help please.
Omar Ghorbel
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What is the pymodbus syntax to assign values to TCP server registers?

I am trying to implement a simple synchronous TCP server using the Synchronous Server Example. However, I do not understand the syntax explanations in the documentation. The example includes the following code block: store = ModbusSlaveContext( …
JLEM
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The pymodbus connection sometimes doesn't respond?

I'm use "pymodbus" lib to connect PLC devices. The device is used Modbus RTU over TCP that devices will return the temperature and humidity of the environment. map address list 0001: temperature 0002: humidity I performed once to get value and…
frank
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How to stop a pymodbus async ModbusTcpServer?

I want to stop a pymodbus async ModbusTcpServer then start a new server. Therefore, I've tried with the following simplified code snippet, but I got an error: from pymodbus.server.async import StartTcpServer, StopServer from pymodbus.device import…
Benyamin Jafari
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