canmetry

User guide

Canmetry Community is a browser-based CAN log analyzer for loading raw bus logs and DBC files directly in the browser. The community edition is fully client-side: files are read locally, parsed locally, and decoded locally.

Workflow

Load log  →  Load DBC  →  Channel mapping (+ Start)  →  Graph / Trace / DBC

Typical session:

1. File → Load CAN log… — load BLF, ASC, CSV, LOG, or MF4
2. File → Load DBC… — add one or more .dbc files
3. File → Channel mapping… — assign DBC files to CAN channels, then click Start parsing on the mapping card
4. Switch between Graph, Trace, and DBC

You do not need a separate File → Parse signals step after mapping; Start parsing on the card begins decode.

Optional actions:

• File → Parse signals — re-run decode later if needed
• File → Export signals (CSV)…
• File → Save project…
• File → Import project…

Graph

Graph is the decoded signal workspace. It combines a searchable signal list, per-signal properties, grouping, and an interactive chart for time-domain analysis.

What Graph is for

Use Graph when you want to:

• inspect decoded signal values over time
• compare multiple signals on one chart
• isolate related signals into groups
• inspect exact values at one or two cursor positions
• zoom into one time window and keep that layout in a project file

Layout

Area	Purpose
Left signal table	Current plotted signals, visibility, Y value, ΔY, hex display, remove
Group controls	Create groups, switch group view mode, remove groups
Add signal action	Open searchable signal picker dialog
View options	Show/hide table columns such as message, unit, description
Right chart	Overlay or stacked signal rendering
Chart toolbar	Zoom mode, cursor mode, reset, shortcuts/help

Signal catalog and add flow

After parsing, Graph builds a decoded signal catalog from the mapped DBC files and the current log.

You can:

• open the signal picker with Add Signal
• search by signal name, message name, unit, or description
• add one signal or multiple signals incrementally
• rely on the app auto-adding the first decoded signal in a fresh session

Signal properties shown in Graph

For each plotted signal, Graph can surface:

• signal name
• message name
• unit
• description
• current Y value at the main cursor
• delta Y at the diff cursor
• raw/hex view where relevant
• visibility state
• color

Signals also preserve channel context, so the same signal name on different channels remains distinct.

Visibility, color, and row actions

Plotted signals are not forced to stay visible all the time. For each signal you can:

• toggle visibility without removing it from the workspace
• remove it from the plotted list
• assign a custom color
• reset a custom color back to the default palette

The context menu is designed so you can refine the chart without rebuilding the plotted set from scratch.

Grouping

Graph supports lightweight signal grouping to keep large sessions readable.

You can:

• enter group pick mode
• select two or more plotted signals
• create a named group
• switch a group between:
  • overlay
  • stacked
• remove a group while keeping the member signals available

Grouping is useful for:

• same-ECU related signals
• compare-left / compare-right pairs
• speed + torque + pedal bundles
• digital status signals grouped away from analog signals

Chart modes

Graph supports two viewing strategies:

• Overlay — multiple series share one plot region
• Stacked — each series/group gets its own vertical band

Overlay is better for direct comparison. Stacked is better when units and ranges differ heavily.

Cursor system

Graph has two cursor concepts:

• Main cursor
  • follows hover / active interaction
  • shows the current value per visible series
• Diff cursor
  • placed explicitly for comparison
  • computes delta time and delta value

This makes it possible to inspect:

• exact RPM at one time point
• delta speed over one acceleration segment
• latency between two state transitions

Zoom and navigation

Graph is designed for inspection, not just display.

Available interactions include:

• zoom in
• zoom out
• reset zoom
• pan view
• box zoom
• X-only zoom
• Y-only zoom
• cursor-oriented zoom

The visible time window and Y ranges are persisted into project files.

Signal rendering details

The chart uses a custom renderer instead of a generic chart preset so it can support:

• stepped signal paths
• per-series Y ranges
• stacked multi-panel layout
• enum/value-label aware axes
• stable cursor reads and diff calculations

This is especially useful for mixed datasets where some signals are continuous values and others are discrete state signals.

Keyboard shortcuts

Graph includes a shortcuts/help entry from the toolbar. The shortcuts are aimed at high-frequency workflows such as:

• open picker
• open help
• navigate chart tools faster

Best use cases

Graph is the best view for:

• throttle / speed / RPM relationships
• state transitions over time
• compare two points on one drive event
• building saved workspaces for repeated analysis

Trace

Trace is the raw frame inspection view. It keeps the original CAN frames visible while layering on search, filtering, decoded message names, and row-level signal decode.

What Trace is for

Use Trace when you want to:

• inspect original traffic rather than only decoded signals
• find one arbitration ID quickly
• verify payload bytes against a DBC definition
• compare repeated frames of the same message
• inspect how bits change over time

Layout

Area	Purpose
Summary bar	Shown frame count, total frame count, time span
Copy actions	Copy selected row ID, data bytes, or a tab-separated row
Filter controls	Narrow by ID, bytes, channel, type, time window
Search controls	Search ID / data and jump through matches
Frame table	Raw frame rows with names, channel, type, DLC, payload
Detail panel	Selected row metadata, decoded signals, bit activity

Frame table

The main table includes:

• row number
• relative time
• node name (when DBC mapping resolves one)
• channel
• arbitration ID
• decoded frame/message name
• message sparkline/activity hint
• direction
• DLC
• data bytes

Trace keeps rows even when no DBC matches, so you can still inspect unidentified traffic.

Filtering

Trace supports a filter model tuned for CAN log work:

• ID query
• channel
• frame type
  • CAN
  • CAN FD
  • ERR
• data bytes query
• time from / time to in seconds

Filter state is applied on top of the raw extracted frame list.

Search and match navigation

Search is separate from filtering.

You can:

• search by ID text
• search by byte pattern
• jump to previous/next match
• keep the filtered context while moving among matches

This makes Trace useful for spot checks without losing the larger filtered view.

Sorting and row selection

Trace can toggle time ordering and keeps one selected row active.

Selecting a row updates:

• decoded signal list for that frame
• metadata panel
• same-message frame slice used by the bit activity view

Detail panel

The selected-frame detail panel is where Trace becomes decode-aware.

It shows:

• message name
• arbitration ID
• channel
• timestamp
• frame type
• data bytes
• decoded signals for that specific row

If a row resolves to a DBC message, each decoded signal value is displayed beside the raw row information.

Copy helpers

Trace includes direct copy buttons for:

• arbitration ID
• data bytes
• full row summary

This is useful for:

• bug reports
• engineering notes
• pasting into docs or spreadsheets
• comparing with external tools

Sparkline overview

Trace builds per-message sparklines / compact activity summaries so repeated traffic is easier to scan visually.

These are especially useful when the table contains many repeated cyclic messages.

Bit activity heatmap

For the currently selected message ID, Trace can compute a per-bit activity summary from repeated frames.

The heatmap helps answer questions like:

• which bits are changing often?
• which bytes are mostly static?
• is this payload carrying counters, state flags, or analog values?

Requirements:

• at least two frames for the same arbitration ID
• same selected message scope

Best use cases

Trace is the best view for:

• reverse engineering
• payload validation
• frame-level debugging
• checking whether DBC decode is plausible

DBC

DBC is the database inspection view. It lets you browse message definitions, signal properties, nodes, network metadata, value tables, and attributes even before parsing a log.

What DBC is for

Use DBC when you want to:

• inspect a loaded DBC file on its own
• find where a signal lives
• verify start bit / length / byte order
• inspect comments, attributes, and enums
• browse nodes and network-level metadata

Layout

Area	Purpose
File selector	Switch between loaded DBC files
Scope selector	Messages, Nodes, Network
Search field	Filter by name, ID, unit, comment, description
Message list	DBC message overview
Signal table	Signals in the selected message
Bit matrix	Bit/byte layout visualization
Detail side panel	Selected signal details, value table, attributes

Message scope

The default DBC mode is Messages.

It shows:

• message name
• hexadecimal / numeric ID matching
• DLC
• transmitter node
• cycle time when available
• signal count
• comments

Selecting a message updates:

• signal table
• bit matrix
• signal detail side panel

Signal table

For the active message, the signal table exposes:

• signal name
• start bit
• length
• byte order
• value type
• factor
• offset
• min / max
• unit
• multiplexing info
• receivers
• comments

This is the fastest view for verifying whether a payload definition looks correct.

Bit matrix

The bit matrix is a visual representation of the selected message layout.

It is useful for:

• seeing where each signal sits in the payload
• understanding Motorola vs Intel placement
• spotting overlap mistakes
• teaching / documenting signal packing

It follows a Vector/CANdb++-style bit orientation so CAN engineers can read it quickly.

Signal detail panel

When you click a signal, the side panel shows a fuller property sheet:

• name
• start bit
• length
• byte order
• signed/unsigned / value type
• factor
• offset
• min
• max
• unit
• multiplex selector/value
• receivers
• comments
• value table / choices
• signal attributes

Nodes scope

The Nodes tab provides a node-centric view of the database:

• node name
• transmit message count
• receive signal count
• comments
• node attributes

This is useful when you want to understand the DBC by ECU / network participant rather than by message.

Network scope

The Network tab exposes global DBC metadata such as:

• version
• bus speed (when available)
• DBC summary counts
• global attributes
• global value tables
• top-level comments

Search behavior

Search is scope-aware:

• in Messages, it checks message names, IDs, transmitter names, descriptions, and signal content
• in Nodes, it checks node names and descriptions
• in Network, it mainly helps narrow the currently loaded catalog context

Best use cases

DBC is the best view for:

• DBC review
• reverse-engineering support
• checking bit layout before decode
• understanding enum/value tables

Local deployment and development

Requirements

• Node.js 20+ recommended
• pnpm

Start locally

pnpm install
cp .env.example .env.development
pnpm dev

Then open the local Vite URL shown in the terminal.

Local production-style preview

pnpm build
pnpm preview

GitHub Pages static build

VITE_BASE_PATH=/your-repo-name/ pnpm build:pages

Output is written to .output/public.

Environment variables

Variable	Purpose
VITE_APP_URL	Public app URL
VITE_APP_NAME	App title / branding
VITE_APP_DESCRIPTION	App description
VITE_COMMERCIAL_URL	Optional link to hosted SaaS / Pro edition
VITE_BASE_PATH	Router / asset base path for subpath deployments

Supported formats

Format	Extension	Notes
Vector BLF	.blf	CAN / CAN FD log containers
Vector ASC	.asc, .log	CANalyzer/CANoe-style ASCII
CSV	.csv	python-can export or Time/ID/Data style tables
ASAM MDF4	.mf4	CAN bus logging groups
DBC	.dbc	Signal decode / DBC inspection

Parsers live under src/lib/can/ and are original browser-side implementations.

Project files

Workspace state can be exported as .blfproject.json.

It stores:

• current viewer tab
• added and visible signals
• groups
• channel mapping
• zoom mode and view window
• Y ranges
• cursor state
• referenced log and DBC filenames

It does not embed the original log or DBC file contents.

To restore a project:

1. import the project file
2. reload the referenced log and DBC files
3. open Channel Mapping and click Start parsing again (or File → Parse signals)

Privacy

Community edition parsing stays on your machine. No server upload is required for decode or charting.

Static deployment via GitHub Pages or any CDN still serves a browser-side app. If you later add a commercial link, VITE_COMMERCIAL_URL only controls the UI link target and does not change the local parsing model.

See also

• README — repository overview and setup
• architecture.md — implementation architecture
• THIRD_PARTY_NOTICES.md — dependency licenses
• LICENSE — MIT

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