Data extraction from a Foxwell NT520 Pro car diagnostic scanner

The Foxwell NT520 Pro, and a few other models from Foxwell Technology, are car diagnostic scanners that can access a lot of manufacturer-specific data.

Most cheap scanners can only access the OBD II engine data, which is required by law to have a standard format. The Foxwell can access that, but can also get at manufacturer-specific data for things like the transmission, brakes, gauges, power windows, and air conditioning.

The unit comes with OBD II and one manufacturer-specific module. You can buy it with the module already loaded, or you can download the module yourself using a proprietary PC application. To get more than one manufacturer-specific module, you have to pay $60 per additional module.

In my case I have the Honda module for a 2007 Acura TL. The scanner will show engine data, transmission data, brake pressure, and even keys registered to the car. You can turn on and test individual dash lights, make the speedometer or tachometer show any value, and probably mess up your car with some of the configuration options.

In addition to real time display and subsystem tests, it can continuously log a series of parameters. Choose Live Data and Save. You can select all parameters for the engine, all parameters for the transmission, or a subset of the parameters. The fewer you log, the faster it samples.

There is a playback option that is supposed to display the stored data. Playback doesn’t work properly. It will display some but not all OBD parameters, and fails entirely for the Honda module.

The Foxwell uses a Micro SD card, so I pulled the card, plugged it into the PC, and went looking for the files. Turns out they are in a proprietary format, and I could not find a converter online, so I wrote my own.

The file extension is .cbf, and the format is basically ASCII strings with null byte terminations and a few binary integers that have to be parsed to make sense of things. The converter will generate either HTML or CSV from the CBF files.

The Foxwell does not log time of day, so it is difficult to match performance data to your location while driving. If you want to mark a point in the engine log, hold down one of the cruise control buttons for a few seconds. Even though you are not using the cruise control, the corresponding “Cruise Sw” column in the engine data will toggle to On.  If you are logging automatic transmission data, the paddle shift buttons will be logged, even though they have no effect with the shift lever in Drive.

You can use the converter online or download the Python code. I have only tested with the OBD and Honda modules. If you encounter any CBF files my converter won’t parse, please send them to me so I can fix it.

Sample files:

Engine CBF Table
Transmission CBF Table
Brakes CBF Table
OBD II CBF Table

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