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Questions tagged [modbus-tcp]

A messaging structure developed by Modicon. It is used to establish master-slave/client-server communication between intelligent devices.

A messaging structure developed by Modicon in 1979. It is used to establish master-slave/client-server communication between intelligent devices. (from http://www.modbus.org/faq.php)

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Can I access an OPC server using a Modbus Master?

I'm trying to access an OPC Server on a Windows Machine using a Modbus Master on Linux and was wondering if that's possible
edoardo849
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Is there a solution to connect a Web app to a Modbus PLCs

I'm developing a Web application with HMI capabilities that needs to interface with multiple Modbus RTU and Modbus TCP PLCs: frequently update the web UI based on the state of the Modbus devices send commands to Modbus devices based on the user's…
astreltsov
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Send "LED Flash" command using libmodbus

Is it possibe and if so to send LED Flash command to IFM AY1020 device using libmodbus? I can archive it via browser: But i need to do it from C code.
pzydziak
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How to malloc modbus_t

I write generic application for handle as many modbus devices as defined in JSON config file. mbus_servers struct used in my_modbus_init() contents ip of device and port. Initialization of one modbus_t in my_modbus_init() looks like this: modbus_t…
pzydziak
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How to add a library (header + .c) compilation in MakeFile (Eclipse) ?

I'm working on a project, coding in C++, to develop a communication Modbus over TCP/IP between a Raspberry pi and an Arduino. I have a basic exemple of "hello world" which works in Raspberry. I want to add the libmodbus library (.h and .c files) in…
Steve Dsp
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Communication in ASP.NET Core

Situation: I need to create some kind of controlling part of the communication over Modbus TCP/IP in my ASP.NET Core project. Communication is working correctly with Modbus, but I need to read some Modbus addresses pernamently and I need to set them…
David Pavelka
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Collect and change data into a PLC

I am working on a project to collect and change the data into a PLC. I would like to work with any PLC manufacturers so I guess the best way is to create my own modbus communication protocol and not use the OPC protocol (to avoid to be dependant of…
Cedric
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Nmodbus4 library usage

Allow data types such as float, string , double , long and short in the library called Nmodbus4. But I don't know how to implement for string and float , But integer and Boolean implementation was already done. Please any one can help me to find…
MANIKANDAN
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ModbusTCP - wrong ID in generated frame

I have weird problem. I try to communicate with ifm AY1020 via modbusTCP using libmodbus from PC. My code looks as follow: #include #include #include #include #include #include…
pzydziak
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Snort Rule: Save number to check later

I am trying to implement Snort rule that will check if the specific field of the Query (transaction id,Modbus Protocol) will be the same in Response. If not then alarm.The question is if it is possible to implement and if yes how?
AlexP
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How can we read data from all 65536 registers using MODBUS protocol using Spark Streaming?

I have a specific condition where I want to read data from MODBUS protocol. But it only allows me to read 120 registers at once.If I increase this count it gives me ERROR CODE=3 I am using JAMOD for this. Is there a way in which I can read data…
Shivansh
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Receive Heart, smiles from Modsim via TCP/IP

I'm trying to communicate Modrssim (Modbus Simulator) with a java class. I'm sending a query to modsim and it responds to that. But when I try to read the response I can't get the proper character. Here is my code: import java.net.*; import…
Hemang
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Limitation in QModbusTcpClient's data size

The story behind: Using a QModbusTcpClient I am trying to read the content from a device connected to a Modbus/TCP network. For that purpose I have written a Windows program (tested on 7 and 10) in Qt C++ (Qt version 5.7.0) which essentially calls…
scopchanov
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Need to send a heartbeat over Modbus TCP and Read/write registers

So I've got some battery management software which communicates over modbus tcp. I've downloaded Modbus Master (some free modbus testing software) and I've been able to successfully read and write registers BUT for the software to work it has to…
Shane
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Unexpected number when reading PLC using pymodbus

I am using pymodbus to read a register on a Wago 750-881 PLC. I am also reading the same register on the Modbus Poll utility, as well as, an HMI. The Modbus Poll and HMI are reading correctly, but the pymodbus program is not. Here is the code: from…
Mike C.
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