DBC Guide

CanMessenger::DBC parses DBC text and maps signal values to raw CAN bytes.

Load a DBC File

dbc = CanMessenger::DBC.load('example.dbc')

You can also parse inline content:

dbc = CanMessenger::DBC.new(File.read('example.dbc'))

Supported DBC Elements

Current parser support is intentionally narrow and focused:

• BO_ message definitions.
• SG_ signal definitions in the common start|length@endian+/- (factor,offset) pattern.
• Skips BO_TX_BU_ lines.

If your DBC uses advanced constructs (for example multiplexing or uncommon syntax variants), validate with tests before relying on runtime behavior.

Encode by Message Name

frame = dbc.encode_can('Example', Speed: 42)
# => { id: 256, data: [42, ...] }

Validation performed during encoding includes:

• Unknown message name rejection.
• Signed/unsigned range checks.
• Signal bit-bound checks against message DLC.

Decode by CAN ID

decoded = dbc.decode_can(frame[:id], frame[:data])
# => { name: 'Example', signals: { Speed: 42.0 } }

Returns nil if no message with matching CAN ID is found.

Big-endian and Little-endian Signals

• @1 is treated as little-endian.
• @0 is treated as big-endian (Motorola/sawtooth indexing).

2.1.0 includes corrected multi-byte big-endian bit mapping and stricter unsigned overflow checks.