Hi everyone,
I recently organized and released two Modbus debugging tools that I maintain personally, and I would like to share them here for testing and feedback.
The first one is MBSim, a Modbus RTU/TCP slave simulator. It is mainly designed for testing PLC, HMI, SCADA, or host-side Modbus applications when no real slave device is available. It can be used to simulate Modbus devices, test master read/write operations, check register mapping, and debug RTU/TCP communication.
The second one is ModbusGateway, a Qt-based Modbus TCP ↔ RTU software gateway. It forwards requests and responses between Modbus TCP and Modbus RTU, supporting both “TCP master to RTU slave” and “RTU master to TCP slave” scenarios.
Licensing note:
MBSim: free to use, but not open source. Source code is not published.
ModbusGateway: MIT License, source code is available.
Downloads / repositories:
MBSim: GitHub - louisir/mbsim-dist: Official binary releases for MBSim, a freeware Modbus RTU/TCP slave simulator for PLC, HMI, SCADA, and industrial communication testing. · GitHub
ModbusGateway: GitHub - louisir/ModbusGateway: A Qt-based Modbus TCP/RTU gateway that forwards requests and responses between TCP and serial RTU devices. · GitHub
I am especially interested in feedback on:
MBSim compatibility with different PLC, HMI, and SCADA software
Whether RTU serial settings, TCP listening, and register mapping match real-world usage
ModbusGateway stability and exception handling during TCP ↔ RTU conversion
Useful future features, such as multiple slaves, multiple TCP clients, register-table import, exception-code simulation, or scripted responses
If this kind of tool-sharing post is not suitable for this section, please let me know and I will remove or adjust it. Thank you.