CANViewer

cross-platform CAN bus monitor, built on Python.

日本語の説明はこちら

---

This application is a tool that connects an SLCAN or gs_usb-compatible CAN device to a PC and allows you to easily verify CAN communication from your PC. It supports receiving data flowing on the CAN bus, periodic and one-time transmission, switching between standard and extended IDs, and decimal to ↔️ hexadecimal conversion. It is written in Python and runs on Mac, Ubuntu, and Windows.

App Downloads

You can download a pre-built application from Releases. It runs on Windows, Mac and Linux (binary).

CANViewer Features

• Single-shot transmission : press Start button without entering `Interval
• Interval transmission : Input the interval (in milliseconds) you want to transmit interval in Interval and press Start button.
• Switch standard/extended format : Click StdID/ExtID to switch format
• Change input decimal number : Click DataFrame label to switch. Also, you can switch input method to HEX by Ctrl+H(J) and to DEC by Ctrl+D(F).
• Filter function : Ctrl+P switches to Pro mode; in Pro mode, a table for filter settings is displayed, and by entering an ID to be ignored, messages with the specified ID are hidden from the log. (Currently, only the filter function is implemented in Pro mode.)

Interval transmission

Switch between standard ID and extended ID formats

Switch input format between decimal(DEC) and hexadecimal(HEX)

filter function for IDs you want to ignore

Development Prerequisites / What you need for development

• CAN device must be available (for SLCAN or gs_usb, CANable2.0 or MKS CANable)
• Python must be installed.
  • If uv is not installed, it must be installed beforehand. On macOS, you can install it with brew install uv.
  • Resolving dependencies using uv will automatically install the packages needed to run your Python application.
• It is useful to have make included!

For maintenance commands, dependency updates, CI, and release builds, see Development Guide.

How to build

1. Open in terminal

2. Go to the directory where the CANViewer Python application is stored.

   cd CANViewer-directory

3. Use uv to resolve dependencies and create virtual environments.

   uv sync --all-groups

   or

   make install

4. Launch the application with command.

   uv run python main.py

   or

   make run

5. Options for operating with gs_usb

   uv run python main.py -c gs_usb

Build the application bundle

On macOS, this creates dist/CANViewer.app.

make build

To create dist/CANViewer.dmg as well:

make build-dmg

On Linux, this creates dist/CANViewer-<arch>.AppImage.

make build-appimage

To install the AppImage into ~/.local/bin and register a desktop entry:

make install-linux-desktop

LICENSE

This project is LGPL licensed. Please check LICENSE for more information.