Import and Decode Vehicle Data

Import and decode vehicle network log files in MATLAB using Vehicle Network Toolbox (VNT).

When to Use

• Reading .mf4/.mdf/.dat, .blf, .asc, or .txt vehicle bus log files
• Decoding raw CAN/CAN FD frames to signals via DBC or ARXML databases
• Decoding LIN frames via LDF databases (R2025a+)
• Handling polymorphic return types from VNT read functions

When Not To Use

• Simulink CAN configuration
• Live CAN channel access
• XCP/A2L workflows

Prerequisites

Before calling BLF/ASC/TXT import or CAN/CAN FD/LIN decode functions, call detect_matlab_toolboxes to confirm Vehicle Network Toolbox is installed. If unavailable, tell the user. Once confirmed in a session, do not re-check.

MDF functions (mdfRead, mdfChannelGroupInfo, mdfInfo, mdfChannelInfo) are base MATLAB (R2023a+) and do not require VNT. Do not use the deprecated mdf() object constructor -- always use the functional API.

Decode Pipeline

Database Loading

db = canDatabase("path/to/file.dbc");       % CAN and CAN FD
db = arxmlDatabase("path/to/file.arxml");   % CAN only (not CAN FD)
linDb = linDatabase("path/to/file.ldf");    % LIN (R2025a+)

Load once, pass to all decode calls. Multiple databases: canMessageTimetable(tt, [db1, db2]).

Key Constraints

• Polymorphic returns: All VNT read functions (canSignalImport, blfread, mdfRead, canMessageImport) return different types based on channel count and parameters. Always guard with iscell()/istimetable()/isstruct().
• ARXML + CAN FD: arxmlDatabase does not work with canFDMessageTimetable or CAN FD data. Use canDatabase (DBC) for CAN FD.
• No `canFDSignalTimetable`: Use canSignalTimetable for both CAN and CAN FD signals.
• BLF LIN requires `ProtocolMode="LIN"`: Without it, blfread returns only CAN data.
• No signal-level LIN decode: Only linMessageTimetable exists. Access signal values from timetable columns directly.
• MDF raw CAN detection: Use channel name prefixes CAN_DataFrame / LIN_Frame (ASAM standard). Do not use SourceBusType metadata -- it is vendor-specific and unreliable.
• `canMessageImport` default format: Returns legacy can.Message array. Always pass OutputFormat="timetable".
• Cell extraction: Multi-channel calls to blfread, mdfRead, and canMessageImport return cell arrays. Extract with {n} before processing.
• Use `canSignalImport` for ASC/TXT signals: It decodes in one call. Only use canMessageImport when raw message timetables are needed.

File-Specific References

• ASC import -- canSignalImport/canMessageImport with Vector and Kvaser vendors, polymorphic return type handling for multi-channel files
• BLF import -- blfinfo for file inspection, blfread with and without ChannelID, CAN vs LIN protocol selection
• MDF import -- mdfRead/mdfChannelGroupInfo/mdfChannelInfo, detecting raw CAN/LIN groups by channel name, reading specific groups

Protocol References

• CAN decode -- canMessageTimetable and canSignalTimetable pipelines, DBC and ARXML database usage
• CAN FD decode -- canFDMessageTimetable pipeline, why ARXML does not work for CAN FD
• LIN decode -- linMessageTimetable usage, accessing signal values from timetable columns (no signal-level function exists)
• Database objects -- canDatabase vs arxmlDatabase vs linDatabase, which decode functions accept which database type

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