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CANBus Whispering

3 min read

In previous articles, we’ve looked at what makes the CANBus and why we need it. We’ve also looked at the hardware needed to connect a PC to it. So, let’s look at the software element and make a connection!

BusMaster software

BusMaster from Bosch/ETAS
BusMaster from Bosch/ETAS

My preference for connecting to a CANBus is the BUSMaster program. This is an opensource software tool created by a joint project between BOSCH and ETAS. While it hasn’t been actively supported by the parent companies since 2016 and is not bug-free. That said, the functionality content is huge and there is no license fee to maintain.

Just download the installer from github and run it to install on Windows. I use it with Win7 without problems. On Win10 BusMaster needs to be run as administrator to access the USB adapter. Of course, you could build and run your installer from the source, but that’s way over my head.

OBD-II connector for CANBus connection

Freelander2 2013 OBD-II CANBus connection Pin Out
Freelander2 2013 OBD-II CANBus connection Pin Out

So the next step is to connect our chosen USB CANBus adapter to the vehicle, in this case, the Freelander2. We’re going to be plugging into the “On-Board Diagnostic” (OBD-II ) connector which is found at the bottom of the steering column on the Freelander2. To do this we will need an OBD-II plug and a couple of D-SUB9 connectors with the right gender to match the USB CANBus adapter.

Connect the OBD-II port to the USB CANBus adapter following the connection details which came with your adapter, and the pinout diagram above.

BusMaster setup

BUSMaster - Setup Driver and Channel
BUSMaster – Setup Driver and Channel

Okay, to BusMaster! First, we need to do some setting up. As in the picture above you’ll need to set up your Driver (1) and Channel Configuration (2).

If you have a 2 channel adapter, then I recommend connecting the HS bus (High Speed, 500Kbpd) to channel 1 and MS bus (Medium Speed, 125kbps) to channel 2. If you only have a single channel adapter then I would suggest you start out looking at the Medium Speed. As we are connecting to a live vehicle do not install a terminating resistor.

Once you’ve set up the driver and channels, save the configuration (click on the BusMaster in the top left corner). Close BusMaster connect the adapter to the car, turn on the ignition, reopen BusMaster and click connect!

Reading the connected CANBus data

MS Log from Freelander2 in BusMaster
MS Log from Freelander2 in BusMaster

All being well you’ll see something like the screen above, with the timestamps of the data continually changing. You have made your first CANBus connection. Congratulations, you are now a CANBus whisperer and can hear what the car is saying. I wouldn’t advise telling people you meet about your new-found skill . . .

Will it work first time?

Okay, so being realistic, there is a good chance this won’t work first time out of the box. I’ve just installed BusMaster, the CANBus adapter drivers and made the trace above on a fresh installation of Win10, so it can be done. The biggest battle will probably be with the adapter drivers. This is why I prefer the Vector toolchain, they aren’t stupid proof, but they are reasonably easy to fault find.

So are you feeling lucky? Ready to go it alone and connect to the car? Maybe you’d like to read the next article which will deal with how to resolve a CANBus crash as a result of human error.

M

prev: Getting on the CANBus
next: I canee do it!

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