# \[Tool Share / Feedback Wanted\] Two Modbus debugging tools: MBSim slave simulator + ModbusGateway TCP/RTU software gateway

**URL:** <https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664>\
**Category:** Automated Testing\
**Tags:** modbus\
**Created:** [May 22, 2026, 1:54pm UTC](https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664 "2026-05-22T13:54:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![louis.androidor](https://avatars.discourse-cdn.com/v4/letter/l/48db29/32.png) [@louis.androidor](https://forum.inductiveautomation.com/u/louis.androidor)\
**Post date:** [May 22, 2026, 1:54pm UTC](https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664/1 "2026-05-22T13:54:51Z")

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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](https://github.com/louisir/mbsim-dist)  
ModbusGateway: [GitHub - louisir/ModbusGateway: A Qt-based Modbus TCP/RTU gateway that forwards requests and responses between TCP and serial RTU devices. · GitHub](https://github.com/louisir/ModbusGateway)

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.

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [May 22, 2026, 2:05pm UTC](https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664/2 "2026-05-22T14:05:27Z")

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> [@louis.androidor](#):
>
> post is not suitable for this section

I would think it suitable. It might get more visibility in the General Discussion category.

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**Author:** ![louis.androidor](https://avatars.discourse-cdn.com/v4/letter/l/48db29/32.png) [@louis.androidor](https://forum.inductiveautomation.com/u/louis.androidor)\
**Post date:** [June 10, 2026, 7:35am UTC](https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664/3 "2026-06-10T07:35:22Z")

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Thanks, that makes sense. I thought this section was suitable too, but General Discussion may indeed get more visibility. Please feel free to move it if appropriate.