MachineLogMonitor

MachineLogMonitor is a PySide6 desktop application for observing live text logs from CAN, RS232, and CAN trace files. It only reads: no CAN frame and no serial byte is sent from application code — the source layer contains no send or write call, enforced by a test. On CAN, listen-only mode is requested where the backend supports it.

Features

• Monitor exactly one selected source: a CAN bus, an RS232 serial port, a CAN trace file, or a local pipe (Windows named pipe, Linux FIFO) that either the sending program or the monitor creates, so a command-line redirect works too
• Receive-only by design — no send or write call exists in the source layer
• Multiple filtered monitor views (substring or regular expression) over one shared ring buffer; pause and clear per view without losing incoming data
• Configurable substring rules that color lines as DEBUG, INFO, WARN, and ERROR
• Optional arrival timestamp in front of every line (HH:MM:SS.mmm or with the date), in the monitors and in the per-monitor log files, switchable at runtime
• Optional logging to disk: raw stream and per-monitor files, written while a source is connected
• Trace playback at 0.5×, 1×, 2×, 10×, or instant speed
• RS232 port field offers the serial ports detected on the machine and also accepts pyserial URLs (for example socket://host:port)
• A configured serial port that is not present is flagged on the Monitors page and in the menu bar; connecting stays possible for virtual ports
• Sidebar collapses to a narrow icon strip with the arrow button at its top or Ctrl+B
• JSON configuration with safe defaults: missing keys are restored, a malformed file is never overwritten until an explicit save
• Reopens the last used configuration on start and asks before discarding unsaved changes on exit
• Optional dependency vulnerability scan on the About page via pip-audit

Installation

Requires Python 3.10 or newer. Developed and tested primarily on Windows. On Linux, install Qt's system libraries first: the user guide's Getting started page (section Install on Linux; the guide ships in the package under machinelogmonitor/resources/guide/ and opens from the About page) lists the Debian/Ubuntu packages, the dialout group for serial ports and the SocketCAN setup.

pip install machine-log-monitor

As a standalone application, installing with pipx keeps it in its own environment and puts the machine-log-monitor command on the PATH:

pipx install machine-log-monitor

Connecting to a source additionally needs a CAN backend, a serial device, or a supported CAN trace file.

The source distribution also carries the test suite and, under manual_test/, the log generator that feeds the monitor simulated lines without hardware. That generator sends; it is test tooling, not part of the application, and installing the package does not install it.

Usage

Run machine-log-monitor, or its short alias mlogmon, to launch the application:

machine-log-monitor
machine-log-monitor --config .\monitor.json
mlogmon --config .\monitor.json

The application opens on the Monitors page. Configure and select a source under Data source, then choose Connect. Add, edit, or remove filtered views on Log monitors; Pause and Clear affect only the selected view, not the incoming buffer. Enable Log file to also write the received stream to disk.

On General, set the substrings used for DEBUG, INFO, WARN, and ERROR coloring; empty substrings disable that rule. The Timestamp chips there put the arrival time of every line in front of it, in the monitors and in the per-monitor log files; the raw log file stays as received. The Sources card there hides source types you do not use from the Data source page and the Data Source menu. Save settings with File → Save or Save as… as a JSON file that can be passed back via --config.

The optional audit extra (pip install machine-log-monitor[audit], or pipx install "machine-log-monitor[audit]") enables the background pip-audit scan on the About page.

License

MIT — see the LICENSE file shipped with the package. Third-party components (PySide6, python-can, pyserial, bundled fonts) keep their own licenses; see THIRD_PARTY_LICENSES.md, also shipped with the package. The About page opens both files, this README and the CLI reference in a viewer inside the application.

MachineLogMonitor is a diagnostic viewer and not intended for safety-critical use.

This project was created with the assistance of artificial intelligence.