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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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What is the best way to change from polling to events?

If you were to parse 300 bytes of raw data 20 times a second into a bunch of WPF control properties, what would your solution be? More specifically, I have a Modbus-enabled PLC and I need to make a WPF HMI for controlling it. Modbus is a…
Yegor
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Can’t read register of Modbus using python via 485

The transducer is modbus. Via R485 I want to send the request x00 and read it back. x00 is to read the temperature The transducer is expecting hex example: x00 import serial # import the module ComPort = serial.Serial('COM4') # open…
KurtA
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minimalmodbus: No communication with the instrument (no answer) ModBus RTU via Ethernet for SDM630

I am using a Pi4B to try to read data from a SDM630 energy meter. Because the meter is far from the Pi I us a HF2211 ethernet to RS485 converter to bridge the distance. the HF2211 is in transparent mode so the payload of the ethernet messages is…
RobD
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How to request Ebox wifi with modbus

I've never used modbus before. I have an eBox-Wifi Epever connected to an MPPT charge controller TRIRON for solar power. I was able to make it connect to my wifi and now has an accessible IP : 192.168.39.149 I just want to extract some data from it,…
bob dylan
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What is "Must be handling a user gesture to show a permission request." errror message in Chrome Web Serial API?

I am a real beginner when it comes to programming. It is my intention to control a device with the API integrated in Google Chrome via the COM port RS485. I try to reproduce the following tutorial: https://web.dev/serial/ The following error message…
5-HT2A
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Minimalmodbus: read multiple slaves on same serial port

I have a setup with 2 SDM120 kWh energy meters daisy chained on the same serial port (in the future I want to add a SDM630). I found "Using multiple instruments" in the MinimalModbus communication. I succeed in reading registers on the SDM120 on…
m2ts
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Get the 4 bytes of a double with Dart

I have the following problem that I couldn't find a solution. I have a double variable that has a value of 2.1 and I want to get the 4 bytes that represent it. For this I use the following code var valueFloat = new Float32List (1); valueFloat [0] =…
Juan Corica
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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 ping meter with Modbus

I am trying to ping a Socomec meter using the Modbus protocol, having researched, I found NModbus, a C# library. I have never used libraries or C# before (normally Java), but I have to dive right in. I set myself up with Visual Studio Express for C#…
marked
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Block incoming data from C# NetworkStream after timeout has passed

I have a strange question that involves NetworkStreams in C# .Net Core 2.2.101 My setup is as follows: I have a list of meters Each meter has a list of registers (a register saves a value, for example: the voltage or current) Meters are connected…
Morné Lombard
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modbus-tk for Modbus RTU, read/write multiple registers (fn code 23), returns exception code 1

I am using modbus-tk to serially communicate with a device via Modbus RTU over a RS-485 network. I am trying to figure out how to use function 23, READ_WRITE_MULTIPLE_REGISTERS. This is my first time using function 23. Here is my current…
Intrastellar Explorer
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How to implement Modbus on Raspberry Pi?

I'm currently engaged in a project where I'm trying to implement Modbus with the Raspberry Pi 4 as master and controlling a number of actuators as slaves. For this purpose I've purchased a special shield for my Pi. I've run a demo test program that…
OverDemon
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Modbus Master -slave communication

Requirement : Collect the data from Serial port-1 over Modbus, mirror the same on Serial port-2. I'm able to communicate between Master and slave but not able to mirror the data to Serial port 2. Please suggest me how to achieve this. Code :…
APS
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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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