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Questions tagged [modbus]

Modbus is a serial communications protocol published by Modicon in 1979 for use with its programmable logic controllers (PLCs). Simple and robust, it has since become a de facto standard communication protocol, and it is now amongst the most commonly available means of connecting industrial electronic devices.

Modbus is a serial communications protocol published by Modicon in 1979 for use with its programmable logic controllers (PLCs). Simple and robust, it has since become a de facto standard communication protocol, and it is now amongst the most commonly available means of connecting industrial electronic devices.

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Pymodbus Read/Write Floats (REAL)

I have modbus mapping setup in my AB Micro820 PLC. I have an array in 40001 for writing, and one in 42001 for reading. Both are 200 elements and REAL type (32-bit float). I can write and read currently, so I know the code works, just incorrectly.…
xinthose
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Is this endianness conversion correct?

I'm reading through a library (github.com/adduc/phpmodbus) and there's this function for converting integer to little-endian or big-endian string of bytes: private static function endianness($value, $endianness = 0) { if ($endianness == 0) …
MightyPork
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EDS for CANopen and Modbus

The device I'm developing has to support both CANopen and Modbus (RTU and TCP) communications. Is there any format of Electronic Data Sheet (e.g EDS or XDD) that can be used to define both? I have tried using a couple of tools (Vector CANeds and…
Evil Dog Pie
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Modbus Custom Message & Sub functions (NModbus, TCP, Subfunctions)

I am using NModbus in a C# project, to read & write Modbus data from/to a number of I/O devices. I am using the Modbus TCP/IP protocol (ModbusIpMaster etc..) in the program. I have successfully communicated with the devices (through a Modbus…
user1938908
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Looking for Python code to act as a MODBUS slave

Does anyone know of an easy to use Python program that acts as a MODBUS slave? I need to do some integration testing with a MODBUS master. Code can be for serial or TCP. TY, Fred
fred basset
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Twincat3: Can't connect to LabVIEW's Modbus TCP/IP server via Tc2_ModbusSrv library (on virtual PLC)

I am trying to create a simple Hello World Modbus TCP/IP program using Twincat3 and virtual PLC (PLC running locally on my computer). I have set up a LabVIEW Modbus TCP/IP master + slave program (both of which are working see screenshots below). I…
Jakub Szlaur
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Home Assistant with MODBUS

Integrating a MODBUS installation with Home Assistant MODBUS controller in the Gavazzi SH2WEB24 Home Assistant Configiguration.yaml: modbus: name: SmartHouse type: tcp host: port: 502 # SmartHouse Functions switch: platform:…
Davy
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Qt modbus serial port flow control handling

I'm writing a small program using QModbusDevice over the serial port (using the QModbusRtuSerialMaster class) and have some problems. One of the problems seems to be that the flow control of the serial port is incorrect. Checking in a serial port…
Some programmer dude
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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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Telling typescript to to not add ["default'] to new class

TypeScript code import ModbusRTU from 'modbus-serial'; var modbus = new ModbusRTU(); modbus.connectTCP("192.168.1.5", { port: 502 }); modbus.setID(1); setInterval(function() { modbus.writeRegister(2048, 2); }, 100); transpiles to "use…
peter.babic
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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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Auto Discovery of the slave id of modbus device in a network

How to determine whether device connected to the network is modbus device after getting valid ip range through broadcasting mechanism or How to Auto Discover the slave id of modbus device connected to the gateway ?
Ayushi Gupta
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How to set up simple slave and master with modbus-tk RTU (Python)

I wanted to set up a communication between a Raspberry PI (slave) and my PC (Master) through Modbus protocol. Currently, I'm using modbus-tk (python) to set up the communication protocol. The issue is that the Master was not able to read the…
joejoe
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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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