CAN Data Logging Explained

CAN data logging is a cornerstone of modern diagnostics, predictive maintenance, and telematics.  Whether you’re managing vehicle diagnostics, fleet telematics, or predictive maintenance, understanding CAN data logging and the variety of formats can save significant time and boost data analysis capabilities. Here’s a quick overview of the basics, the common formats across brands, and how to make them work seamlessly together.

What is CAN bus?

Before we jump too deep into data logging, let’s take a minute to explain CAN bus. (Read this blog for a deeper explanation of the pros and cons of CAN bus.) CAN bus (Controller Area Network) is a communication system used in vehicles and machines to enable different components, called ECUs (Electronic Control Units), to talk to one another without going through a host computer. This allows systems to share information without as many complicated connections, reducing the complexity of systems and increasing the speed in which components communicate.

An additional benefit of a CAN bus system is that each ECU is self-contained, allowing diagnostics to pinpoint any failures quickly and accurately. 

Applications of CAN Data Logging

While CAN bus was originally developed for automotive use, the system’s simplicity means it is now used in a variety of applications such as assembly lines, industrial vehicles, and heavy machinery.

As such, there are a wide variety of uses that require logging CAN data. Here are some of the top ones we’ve seen over the years:

• Predictive Maintenance: monitoring machinery to predict and avoid breakdowns

• Equipment Blackboxes: storing all data about operations for use in disputes or diagnostics, especially useful for troubleshooting rare issues

• Improve R&D: optimize R&D by collecting usage data automatically and discover issues sooner

• Improve Safety: incentive operators to follow safety protocol by tracking usage

• Reduce Fuel Costs: analyze routes, idling time, and more to optimize fuel performance

• Compliance monitoring: simplify compliance testing by auto-collecting all data

However, in order to use the data sent over CAN, you will need a way to log and extract it. This is where a CAN data logger comes in. 

What is a CAN Data Logger?

At its core, a CAN data logger works by capturing communication between ECUs (Electronic Control Units) on the CAN bus network in vehicles or industrial machinery. Once stored on the data logger's internal memory or SD card, this data can then be used to monitor performance, diagnose issues, and even enable real-time telematics. Typically a lighter weight and more portable option than a laptop, CAN data loggers provide an easy way to store and transmit CAN data.

The Basics of CAN Data Logging

One thing to keep in mind when choosing the best data logger for your needs is the format in which it stores data. CAN data logging formats often vary across brands and models, which can present challenges when trying to standardize data across different devices and applications. Though this can easily be overcome, as we will discuss in the following section.

Common Data Logging Formats

While not a comprehensive list, below you will find the most common formats used for CAN data logging, the benefits of each, and a few products that tend to use them.

1. MDF/MF4 (ASAM MDF)
   MDF, particularly the MDF4 format, is the industry standard for CAN and LIN bus data logging. Developed and standardized by ASAM, it’s widely supported due to its speed, compressibility, and flexibility. MDF4 files are binary-based, enabling fast reading and writing—ideal for handling high data rates. The format supports both raw and physical values, making it versatile for applications ranging from diagnostics to big data analytics. Popular loggers, such as the CSS Electronics CANedge family, store data directly in MDF4 format.

2. CSV
   CSV is one of the most widely accessible formats - readable in basic text editors and spreadsheet applications. However, CSV files lack the efficiency of MDF4 when it comes to speed and data density, making them better suited for lighter, ad-hoc analyses rather than continuous, high-rate data streams.

3. ASC and TRC
   ASC (supported by Vector tools such as CANalyzer and CANape) and TRC (used with Peak PCAN Explorer 6) are common text-based formats that integrate well with various proprietary CAN software. 

Converting CAN Data Formats

If you’ve chosen to log data in MDF/MF4, the first step to interpreting your data is to convert it to commonly used formats, including CSV, ASC, and TRC. This can be done by using a CANedge MF4 Converter. These converters convert MDF4 files to ASC, CSV, or TRC, in either compressed or encrypted formats, allowing data protection while preserving versatility. The data can then be used in tools such as CANalyzer, MATLAB, PCAN Explorer or Excel.

Interpreting CAN Data

However, logging the data isn’t the only step needed in order to use it. Raw CAN data is not human readable. 

This is because it is recorded as CAN signals, which can include multiple pieces of information at once.

To extract the actual value of a CAN signal, the following information is required:

• Byte order: Whether data is encoded Intel or Motorola

• Bit start: Which bit the signal starts at

• Bit length: The length of the signal in bits

• Offset: Value to offset the signal value by

• Scale: Value to multiply the signal value by

DBC Files (CAN data base) are key to interpreting raw CAN data, as they hold the signal decoding rules. Generally, DBC files are proprietary, application-specific, and only available to the OEM (Original Equipment Manufacturer).

Once you have the DBC file, you will also need software that can use your log and the DBC files to transform the raw values into readable formats. These tools enable DBC conversion and visualization, providing human-readable data from otherwise complex CAN frames. Popular options include:

• asammdf GUI - desktop tool, useful for ad hoc analysis, diagnostics and exporting data

• Gradana dashboards - customizable dashboard that allow for data visualization and reporting

• MATLAB/Python Scripts - useful for statistical analysis and processing of large amount of data

With the right conversion tools, you can centralize and standardize data regardless of logging format, improving access and analysis potential across various tools.

Explore CAN Data Logging Solutions

Now that we covered the basics of CAN data logging, it’s time to explore hardware options.

Step 1: Choose Your Hardware

The first step to choosing a CAN data logger is deciding how you want to collect data. Options induce:

• CAN to USB

• For onsite diagnostics and reverse engineering in real-time, CAN to USB is the way to go.

• Recommended logger: CANmod.router

• CAN to SD

• If your goal is to intermittently track data or create a blackbox, CAN to SD is a great choice.

• Recommended logger: CANedge1

• CAN to Cloud

• If you’re looking to log data directly to your server, a CAN to Cloud option is going to be the best fit. 

• This is also the best option for those looking to perform telematics and predictive maintenance or create dashboards. 

• Recommended loggers: CANedge2 or CANedge3

Step 2: Choose Your Adapter Cable

The choice of cable type is often application-specific. Below are popular options to connect your CAN data logger to the CAN network:

• OBD2 adapter - used in most vehicles

• J1939 adapter - typically used in heavy-duty vehicles

• M12 adapter - found in most boats and some industrial machinery

• Contactless - a universal option when you’re not sure or need to switch between systems

While your system may require unique considerations, including needing to log multiple CAN buses in parallel, that’s typically all that is required. 

If you need help choosing the best CAN data logger for your needs, or determining additional system requirements, our expert engineers are here to help.