[Tut] How to Convert .blf (CAN) to .csv in Python

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How to Convert .blf (CAN) to .csv in Python

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Problem Formulation

How to convert

Code:

.blf

from a CAN bus to

Code:

.csv

in Python?

What is BLF? The Binary Logging Format (BLF) is a proprietary
CAN log format from the automative company Vector Informatik GmbH.

What is CAN? The Controller Area Network (CAN bus) is a message-based protocol standard for microcontrollers in vehicles to communicate without a host computer.

Method 1: Using BLF Reader and CSV Writer

To convert the BLF file

Code:

'my_file.blf'

to the CSV file

Code:

'my_file.csv'

, you can first iterate over the bus messages using

Code:

can.BLFReader('my_file.csv')

and add the data to a list of lists. Then, you can use the

Code:

csv.writer()

approach to write the list of lists to a CSV file.

Here’s an example that improves upon this SO thread:

Code:

import can import csv log = [] for msg in list(can.BLFReader("my_file.blf")): msg = str(msg) row = [msg[18:26], msg[38:40], msg[40:42], msg[46], msg[62], msg[67:90]] log.append(row) with open("my_file.csv", "w", newline='') as f: writer = csv.writer(f, delimiter=',', quotechar='\"', quoting=csv.QUOTE_ALL) writer.writerows(log)

A more sophisticated version of this code is provided in this Github repository. Here’s a screenshot of the code — notice the more advanced processing of a single message compared to our solution:

source

Method 2: Using the candas Library

The

Code:

candas

library provides utility functions to work with

Code:

.blf

files and the CAN bus. Among other things, it helps you with the conversion from BLF to CSV as outlined here.

This is the provided example:

Code:

import candas as cd db = cd.load_dbc("dbc_folder") # This is the BLF file 'my_file.blf': log = cd.from_file("my_file") # This prints a signal from the messages in the BLF: print(log["AVGcellTemperature"])

Method 3: Using Custom Solution from python-can Library

You can use your tailor-made solutions by combining the Readers and Writers provided in the

Code:

python-can

library.

It provides multiple utility functions such as:

• Code:

  Listener
  
  
• Code:

  BufferedReader
  
  
• Code:

  RedirectReader
  
  
• Code:

  Logger
  
  
• Code:

  Printer
  
  
• Code:

  CSVWriter
  
  
• Code:

  SqliteWriter
  
  
• Code:

  ASC
  
  
• Code:

  Log
  
  
• Code:

  BLF

Chances are you’ll find what you’re looking for when going over those functions!

Related Video

Still not satisfied? I found the following relevant video when searching for a solution to this problem. I think you’ll find some nice tricks in the video!