MF4 (MDF4) Explained - A Simple Intro [+J1939/OBD2 Data] (2024)

What is an MF4 file (aka MDF4) - and why is it key to CAN bus data logging?

The ASAM MDF (Measurement Data Format) is a binary file format for recording e.g. CAN, CAN FD and LIN bus data. Today, the MDF format is the industry standard - ensuring interoperability across many CAN tools.

The CANedge supports the latest MF4 file format - and below we list benefits, basics and software/API tools. We also provide sample MF4 data (J1939, OBD2).

MDF was developed in the 90's by Vector GmbH and Robert Bosch GmbH. Initially it was proprietary, but in 2002 it was made public - and in 2009 it was standardized by ASAM. The latest version, MDF 4.11, was released in 2014.

Today, the MDF file format is the de facto industry standard - and it is used in an extensive suite of CAN software, APIs - and hardware like the CANedge1, CANedge2 and CANedge3.

In this section, we provide a quick overview of the basic MDF4 file structure - with outset in a CANedge2 raw CAN bus log file.

MDF4 files are comprised of "blocks" - most of which are in practice arbitrarily ordered. Via a system of internal "links", these blocks form a hierarchy.

This structure enables more flexible log files vs. e.g. CSV - ideal for e.g. mixing CAN, CAN FD & LIN or supporting both raw/physical data.

For technical details on MDF files, expand the below:

When you connect the CANedge to your car, truck or other CAN/LIN application, you'll record raw bus data.

To work with the data, you'll need to convert it to human-readable data - aka "physical" or "scaled" values.

In order to convert your raw MDF files, you'll need a database of conversion rules - e.g. a DBC file (CAN database).

With a DBC, you can use e.g. asammdf (see below) to convert your raw data. The resulting MDF file contains a Data Group for each CAN ID and a Channel for each message signal.

You can then easily plot the decoded data in e.g. asammdf - or export it to csv/mat for analysis in Excel/MATLAB.

MDF4 software & API tools

So how do you actually manage your CAN bus MDF4 log files?

Below we list examples of software/APIs that you can use to manage your MDF4 data.

TIP: If you're new to MDF, we recommend the open source asammdf GUI/API and the simple MDF4 converters to get started.

The CANedge is excellent for use with heavy duty vehicles.

In particular it's ideal for vehicle fleet telematics across e.g. trucks, transit buses, excavators, tractors.

The asammdf GUI/API supports decoding J1939 data via J1939 DBC files. To test this, download the sample data below (*.MF4 & DBC) and load it in the asammdf GUI.

J1939 telematics Sample data J1939 DBC

Another popular use case is recording OBD2 data from cars.

Most cars support OBD2 data, letting you analyze e.g. speed, fuel consumption, brake patterns and diagnostics.

A challenge with OBD2 can be in converting the raw data. However, this is easily done with asammdf and our OBD2 DBC. Try it out via the sample files below:

OBD2 logging Sample data OBD2 DBC

CANEDGE2 - PRO CAN IoT LOGGER

asammdf GUI/API - PROCESS CAN DATA

SIMPLE-TO-USE MDF4 CONVERTERS