matlab-import-vehicle-data

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. For reading all groups blindly, mdfRead alone is acceptable. To selectively read or inspect structure first, use mdfChannelGroupInfo or mdfInfo.

Decode Pipeline

Source Format	CAN	CAN FD	LIN	Raw (no decode)
ASC	`canSignalImport(f,"Vector",db)`	same	--	`canMessageImport(f,"Vector",OutputFormat="timetable")`
TXT	`canSignalImport(f,"Kvaser",db)`	same	--	`canMessageImport(f,"Kvaser",OutputFormat="timetable")`
BLF	`blfread(f,Database=db)` -> `canSignalTimetable`	`blfread(f,Database=db)` -> `canFDMessageTimetable` -> `canSignalTimetable`	`blfread(f,Database=linDb,ProtocolMode="LIN")` -> `linMessageTimetable`	`blfread(f)`
MDF/MF4/DAT	`mdfRead` -> `canMessageTimetable(tt,db)` -> `canSignalTimetable`	`mdfRead` -> `canFDMessageTimetable(tt,db)` -> `canSignalTimetable`	`mdfRead` -> `linMessageTimetable(tt,linDb)`	`mdfRead` -> timetable directly

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(). When checking multi-channel results, use iscell() as the primary guard to branch between cell array (multi-channel) vs direct timetable (single channel), then iterate or extract with {n} or {i}.
ARXML + CAN FD: arxmlDatabase does not support CAN FD in MATLAB. It cannot be used with canFDMessageTimetable. When the user provides an ARXML file for CAN FD data, always explain that ARXML does not support CAN FD and they must use canDatabase with a DBC file instead. Do not silently switch to DBC without explaining why.
No canFDSignalTimetable: This function does not exist. 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