BLF Viewer for Window

A portable, zero-install Windows tool for loading Vector BLF measurement files, decoding CAN signals with DBC databases, and plotting them interactively.

Screenshots

Stacked plot:

Multiple Axis plot:

Full tool view:

Features

• Load Vector .blf files — via the open-source python-can library
• Decode signals using .dbc files — full physical value conversion including factor, offset, and unit
• Multi-signal plot — zoom, pan, and interactive cursor with per-signal value readout
• Multi-axis mode — each signal gets its own independent Y axis (overlaid)
• Stacked mode — INCA/CANdb-style layout with one lane per signal, shared X axis
• Show Data Points — toggle sample markers for all plotted signals
• Export to CSV — export selected signals with timestamps
• Raw CAN frame viewer — inspect decoded and undecoded frames
• Save / Load configuration — persist your BLF path, DBC path, signals, and colors
• Portable .exe — single folder, no Python installation required on target machine

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Getting Started

Run from Source

Requirements: Python 3.11 or later

git clone https://github.com/dinacaran/blfviewer.git
cd blf-viewer
pip install -r requirements.txt
python app.py

Download Portable .exe (Windows)

Go to the Releases page and download the latest BLFViewer_vX.X.X_Windows.zip.
Unzip anywhere and run BLFViewer.exe — no installation needed.

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Usage

Step	Action
1	Click Open BLF → select your .blf measurement file
2	Click Open DBC → select the matching .dbc database
3	Click Load + Decode → decodes all signals in the background
4	In the left panel, double-click a signal (or drag it) to plot it
5	Move the cursor over the plot to read time and value
6	Use Multi-Axis or Stacked for different layout modes
7	Click Export Selected CSV to save signal data

Keyboard Shortcuts

Key	Action
Space	Plot selected signal(s) from the tree
F	Fit all plots to window
Delete	Remove selected signal from plot
Ctrl+Up / Down	Reorder selected signal in the plot list
Ctrl+S	Save current configuration

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Build Portable .exe

pip install pyinstaller
pyinstaller BLFViewerPortable.spec

Output is in dist/BLFViewer/ — zip that folder and distribute.

The GitHub Actions workflow (.github/workflows/build.yml) builds and uploads the .exe automatically on every tagged release.

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Project Structure

blf-viewer/
├── app.py                      # Entry point
├── core/
│   ├── blf_reader.py           # python-can BLF reader
│   ├── dbc_decoder.py          # cantools DBC decoder
│   ├── signal_store.py         # In-memory signal series store
│   ├── load_worker.py          # Background QThread worker
│   └── export.py               # CSV export
├── gui/
│   ├── main_window.py          # Main Qt window
│   ├── plot_widget.py          # Interactive plot panel
│   ├── signal_tree.py          # Left-panel signal tree
│   └── raw_frame_dialog.py     # Raw CAN frame viewer
├── requirements.txt
├── BLFViewerPortable.spec      # PyInstaller spec
└── .github/workflows/build.yml # Auto-build on release tag

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Dependencies

Package	Version	License
python-can	≥ 4.3	LGPL v3
cantools	≥ 39.0	MIT
PySide6	≥ 6.6	LGPL v3
pyqtgraph	≥ 0.13	MIT
numpy	≥ 1.26	BSD

All dependencies are compatible with MIT distribution.

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Contributing

Contributions are welcome! Please read CONTRIBUTING.md before opening a pull request.

Found a bug? Open an issue with:

• Your OS and Python version
• A minimal description of the BLF / DBC setup (no proprietary data needed)
• The full error message or unexpected behaviour

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Disclaimer

See DISCLAIMER.md. This tool is for offline analysis only and must not be used in any safety-critical or real-time context.

Vector Informatik GmbH is not affiliated with this project.

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License

MIT — see LICENSE.

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