Free and powerful Modbus Simulator

Professional Modbus Slave (Server) simulator supporting both Modbus-TCP and Modbus-RTU protocols

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OpenModSim Screenshot

Features

Coils Icon

Modbus Functions

Support for all standard Modbus functions: Read Coils, Read Discrete Inputs, Write Single/Multiple Coils, Read/Write Holding Registers

Simulation Icon

Data Simulation

Simulate coil/flag values with Random and Toggle modes. Simulate register values with Random, Increment, and Decrement modes with configurable limits and step

Document Icon

Message Logging

Comprehensive logging of all Modbus communication traffic with built-in Message Parser for analyzing and decoding protocol frames

Wrench Icon

Error Simulation

Simulate Modbus error responses and exception codes to thoroughly test master (client) device error handling

Script Icon

Scripting

ECMAScript/JavaScript scripting support for advanced simulation scenarios. Run scripts Once or Periodically with full access to register and coil values

Computer Icon

Cross-Platform

Available for Windows 7+ and major Linux distributions (Debian, Ubuntu, Fedora, Rocky, OpenSUSE, Alt Linux, Astra Linux, RedOS) with native performance

Screenshots

Data View
Map View
Traffic View
Scripting

Download OpenModSim

Get the latest version for your platform

Windows Installer

Download Windows Installer x64Qt6
Download Windows Installer x64Qt5
Download Windows Installer x86Qt5

System Requirements

  • Windows 7 or newer for Qt5 packages
  • Windows 10 or newer for Qt6 packages
  • 32-bit (x86) or 64-bit (x64) processor

macOS DMG Package

Download macOS DMG arm64Qt6

Open the DMG package

open ./qt6-omodsim2-2.0.0_arm64.dmg

Drag Open ModSim 2.app to the Applications folder

Before the first launch, allow the application to run in System Settings > Privacy & Security, or remove the quarantine attribute

xattr -dr com.apple.quarantine "/Applications/Open ModSim 2.app"

Run the application

open "/Applications/Open ModSim 2.app"

Move Open ModSim.app to Trash or run

rm -rf "/Applications/Open ModSim.app"

Linux DEB Packages

Download DEB Package amd64Qt6
Download DEB Package amd64Qt5

Qt6 package

sudo apt install ./qt6-omodsim2_2.0.0-1_amd64.deb

Qt5 package

sudo apt install ./qt5-omodsim2_2.0.0-1_amd64.deb

Qt6 package

sudo apt remove qt6-omodsim2

Qt5 package

sudo apt remove qt5-omodsim2

Linux RPM Packages

Download RPM Package x86_64Qt6
Download RPM Public Key GPG

Fedora Fedora · Rocky Rocky · RedOS RedOS 

sudo dnf install ./qt6-omodsim2_2.0.0-1.x86_64.rpm

SUSE SUSE · OpenSUSE OpenSUSE

Import public key and install

sudo rpm --import qt6-omodsim2.rpm.pubkey
sudo zypper install ./qt6-omodsim2_2.0.0-1.x86_64.rpm

Alt Linux Alt Linux

Run as root user

apt-get install ./qt6-omodsim2_2.0.0-1.x86_64.rpm

Fedora Fedora · Rocky Rocky · RedOS RedOS 

sudo dnf remove qt6-omodsim2

SUSE SUSE · OpenSUSE OpenSUSE 

sudo zypper remove qt6-omodsim2

Alt Linux Alt Linux

Run as root user

apt-get remove qt6-omodsim2

Build from Source

OpenModSim is open source and can be built from source code. Visit the GitHub repository for build instructions.