Vector DBC Syntax for VS Code

Rich language support for the Vector DBC (CAN database) file format in Visual Studio Code. DBC files define the messages, signals, and nodes of a CAN bus network and are widely used in automotive development with tools such as CANdb++, CANalyzer, and CANoe.

Features

Syntax Highlighting

Tokens are coloured according to their role in the DBC grammar:

Section keywords — VERSION, NS_, BS_, BU_, BO_, SG_, EV_, CM_, BA_DEF_, BA_DEF_DEF_, BA_, VAL_, SIG_GROUP_, SG_MUL_VAL_, BO_TX_BU_, and all relation keywords.
Strings — double-quoted values, with \" escape support.
Numbers — integers, decimals, and scientific notation; signed and unsigned.
Comments — // line comments.
Mux indicators — M, mN, and mNM signal multiplexing markers.
Operators and punctuation — |, @, (, ), [, ], ,, ;, :.
Special identifier — Vector__XXX (the no-node placeholder).

Syntax highlighting of a DBC file showing section keywords, signal definitions, strings, numbers, and comments in distinct colours

Hover Information

Hover over a message ID, message name, signal name, node name, or attribute name to see a structured summary without leaving the editor.

Signal hover — start bit, bit length, byte order, value type (signed/unsigned), scale, offset, min/max, unit, and receiver nodes. If a CM_ SG_ comment exists, it is appended below.
Message hover — DBC ID, decoded CAN ID (with frame type: 11-bit standard or 29-bit extended), DLC, sender node, and signal count. If a CM_ BO_ comment exists, it is appended below.
Node hover — node name and its CM_ BU_ comment if present.
Attribute hover — declared kind, type, range or enum choices, and default value.

Hover tooltip over a signal name showing a table with bit layout, scaling, and unit fields

Document Outline (Symbols)

The Outline panel and Go to Symbol (Ctrl+Shift+O / Cmd+Shift+O) display a structured tree of the file:

Each BO_ message appears as a top-level entry labelled [0xID] MessageName with its DLC and sender as detail text.
Each SG_ signal appears as a child of its message, labelled with the signal name and unit.
A Nodes group lists all BU_ node names.
Environment variables (EV_) appear as top-level variable symbols.

Outline panel showing a tree of messages and their child signals, each labelled with CAN ID and name

Message Block Folding

BO_ message blocks fold and expand independently. Click the gutter chevron or use Ctrl+Shift+[ / ] to collapse or expand a message block, keeping the rest of the file visible.

Editor showing two message blocks — one folded to a single line and one expanded with its signals visible

Find All References

Press Shift+F12 or right-click → Find All References on any symbol to see every location in the file where it is used:

Signal names — all occurrences in CM_ SG_, VAL_, SIG_VALTYPE_, SIG_GROUP_, SG_MUL_VAL_, and BA_ lines.
Message IDs — all occurrences in CM_ BO_, VAL_, SIG_VALTYPE_, SIG_GROUP_, SG_MUL_VAL_, BO_TX_BU_, and BA_ lines.
Node names — all occurrences in message sender fields, signal receiver lists, CM_ BU_, BO_TX_BU_, and BA_ lines.
Environment variable names — all occurrences in CM_ EV_ and BA_ lines.
Attribute names — all occurrences in BA_DEF_DEF_ and BA_ lines.

References can be invoked from either the definition site or any usage site.

Go to Definition

Press F12 or Ctrl+Click on a reference to jump to its definition:

Signal names in CM_ SG_, VAL_, SIG_VALTYPE_, SIG_GROUP_, SG_MUL_VAL_, and BA_ lines navigate to the SG_ definition.
Message IDs in CM_ BO_, VAL_, SIG_VALTYPE_, SIG_GROUP_, SG_MUL_VAL_, BO_TX_BU_, and BA_ lines navigate to the BO_ definition.
Node names in message sender fields, signal receiver lists, CM_ BU_, BO_TX_BU_, and BA_ lines navigate to the BU_ definition.
Environment variable names in CM_ EV_ and BA_ lines navigate to the EV_ definition.
Attribute names in BA_DEF_DEF_ and BA_ lines navigate to the BA_DEF_ definition.

Editor Conveniences

Comment toggling — Ctrl+/ (Cmd+/) toggles // line comments.
Bracket matching — [] and () pairs are matched and highlighted.
Auto-close pairs — [, (, and " are automatically closed.

Installation

Install from the Visual Studio Code Marketplace or search for "Vector DBC Syntax" in the Extensions panel (Ctrl+Shift+X).

Files with the .dbc extension are automatically recognised and highlighted on open.

What is a DBC file?

A .dbc file is a plain-text network database used to describe a CAN bus. It lists:

Nodes (BU_) — ECUs or devices on the bus.
Messages (BO_) — CAN frames, each with a numeric ID, DLC, and sending node.
Signals (SG_) — bit fields within a message frame, with scaling, offset, range, unit, and receiver nodes.
Comments (CM_) — human-readable descriptions attached to messages, signals, and nodes.
Attributes (BA_DEF_, BA_) — custom metadata (e.g. cycle time, initial value).
Value tables (VAL_, VAL_TABLE_) — named enumerations for signal values.

Example snippet:

BO_ 100 ENGINE_STATUS: 8 ECU
 SG_ EngineSpeed M : 0|16@1+ (0.1,0) [0|6500] "rpm" Vector__XXX
 SG_ EngineTemp m0 : 16|8@1+ (1,-40) [-40|215] "degC" DASHBOARD

Limitations and planned features

The following features are planned but not yet implemented:

Rename — rename a signal or node across the entire file.
Completion — node-name suggestions in sender and receiver fields; attribute-name suggestions in BA_ lines.

License

MIT

Vector DBC Syntax Highlighting

Marcus Ahlstrand