QModMaster vs Modbus Poll: Free vs Commercial (2026)
Modbus Poll is the commercial reference Modbus master from Witte Software; QModMaster is the free, open source alternative. Here is an honest, feature-by-feature comparison so you can decide whether the paid tool earns its price for your job.
Feature Comparison
| Feature | QModMaster | Modbus Poll |
|---|---|---|
| License & Price | LGPLv3 — free, including commercial use | Commercial — see modbustools.com for current pricing |
| Platforms | Windows 7/10/11, Linux | Windows |
| Protocols | Modbus RTU + TCP | Modbus RTU/ASCII + TCP/IP (per vendor) |
| Bus Monitor | Built-in — raw hex request/reply view | Data logging and protocol test features (per vendor) |
| Portable | Yes — portable .zip, no installer | Windows installer (per vendor) |
| Scripting / Automation | Scan polling only — no scripting API | OLE Automation for Excel (per vendor) |
| Support | Community only — no official tech support | Commercial vendor support |
Where QModMaster Wins
- It costs nothing (LGPLv3) — field debugging, commissioning, and learning without a license to manage.
- Truly portable: unzip and run from any folder or USB stick; nothing touches the registry.
- Raw-hex bus monitor built in, plus Linux support — handy when your test bench isn’t Windows.
Where Modbus Poll Earns Its Price
- OLE Automation for Excel — drive test sequences and log results straight into spreadsheets, which QModMaster cannot do.
- Data logging and protocol test features aimed at QA labs and long soak tests.
- A polished commercial product with vendor support, trusted by customers for over 25 years (per vendor).
Frequently Asked Questions
Is QModMaster a drop-in replacement for Modbus Poll?
For hands-on debugging — reading and writing registers, watching raw traffic, commissioning devices — yes, QModMaster covers the same ground for free. It cannot replace Modbus Poll’s OLE Automation for Excel or its data-logging workflows.
Does Modbus Poll have a free version?
Modbus Poll is commercial software from Witte Software. Check the vendor’s official site for current pricing, licensing options, and any trial terms before you buy.
Can QModMaster log data like Modbus Poll?
Not in the same way. QModMaster’s Scan mode polls a device continuously and shows live values, but there is no built-in data logging, export, or scripting API.
Which is better for learning Modbus?
QModMaster: it costs nothing, needs no installation, and the built-in bus monitor shows the raw bytes of every request and reply — the fastest way to understand the protocol.