QModMaster vs QModBus: Two Different Tools Explained
Type “qmodbus” into a search engine and you will find two different tools with confusingly similar names: QModBus and QModMaster. They are independent projects, maintained by different developers — this page explains which is which, so you download the right one.
The Short Answer
QModMaster is the free, open source (LGPLv3) Modbus RTU/TCP master simulator from the upstream SourceForge “qmodmaster” project — and it is the tool this site documents, with a tutorial and a full user manual.
QModBus is an independent project by a different developer (EDC Electronic Design Chemnitz GmbH): a free, Qt-based Modbus master for serial RTU only, released under the GPLv2. Its homepage is qmodbus.sourceforge.net.
Similar names, separate projects — neither is affiliated with the other, and this site only covers QModMaster.
Side-by-Side Facts
| Fact | QModMaster | QModBus |
|---|---|---|
| Upstream | SourceForge “qmodmaster” project | qmodbus.sourceforge.net and SourceForge “qmodbus” project |
| Developer | Independent open source maintainer | EDC Electronic Design Chemnitz GmbH |
| License | LGPLv3 | GPLv2 |
| Protocols | Modbus RTU + Modbus TCP | Modbus RTU over serial only |
| Bus Monitor | Yes — raw hex request/reply view | Yes — bus monitor included |
| Function Codes | 01, 02, 03, 04, 05, 06, 15, 16 | See vendor docs |
| Platforms | Windows 7/10/11, Linux (no macOS) | Windows, Linux (per project homepage) |
| Documented on This Site | Yes — tutorial + user manual | No |
Where QModMaster Wins
- Modbus TCP support: QModBus is serial-RTU only. If any of your devices sit on Ethernet, QModMaster is the only one of the two that can talk to them.
- Complete master workbench: full read/write function codes (01, 02, 03, 04, 05, 06, 15, 16), Scan polling, RTS control, and five data display formats — not just basic reads.
- Documented here: step-by-step tutorial and a full user manual on this site, written for beginners.
Where QModBus Still Makes Sense
- It is also free and open source (GPLv2) with its own bus monitor — for a quick pure-serial RTU check, it does the job.
- Smaller scope, less to configure: RTU-only means no TCP settings to get wrong when you never touch Ethernet.
- Long-standing independent codebase from an established electronics design company.
Frequently Asked Questions
Are QModMaster and QModBus the same program?
No. They are two independent projects maintained by different developers. QModMaster comes from the upstream SourceForge “qmodmaster” project and supports Modbus RTU and TCP; QModBus is a separate tool by EDC Electronic Design Chemnitz GmbH for serial Modbus RTU only.
Is QModBus a newer version of QModMaster?
No — neither is a version of the other. They are separate codebases with separate maintainers that happen to have similar names.
Which one supports Modbus TCP?
QModMaster supports both Modbus RTU and Modbus TCP. QModBus supports Modbus RTU over a serial line only, so if your devices are on Ethernet, QModMaster is the one you want.
I downloaded a file called qmodbus — is this the right site?
If your file came from the SourceForge “qmodmaster” project, yes: this site documents QModMaster, with a tutorial, a full user manual, and download guidance. If you were after the EDC Chemnitz serial-only tool, its homepage is qmodbus.sourceforge.net.