The Vehicle Interface (VI) is piece of hardware that connects
to the car’s CAN bus, translates proprietary CAN messages to the standard
OpenXC message format and sends the output over USB, Bluetooth,
or 3G/Ethernet/WiFi to a host device.
The OBD-II port has one standard pin pair for a single CAN bus, but many
automakers expose other buses on additional, non-standard pin pairs. For this
documentation, we’ll use this nomenclature:
|OBD-II Pin Pair||OpenXC Bus Name||Other common name|
|6 (+) and 14 (-)||CAN1||CAN high / CAN low from ISO 15765-4 and SAE-J2284|
|3 (+) and 11 (-)||CAN2-1||Ford secondary, Chrysler CCD|
|1 (+) and 8/9 (-)*||CAN2-2||Ford: infotainment, GM: J2411|
|* If available, Pin 8 on Ford B, C platforms and Pin 9 on Ford D platforms. This is typically not available.|
Most vehicle data is available from CAN1, and all vehicle interfaces connect
to that bus. Some data is available only on CAN2-1 or CAN2-2, and
these buses are not connected to all available VIs (see below). To find out
if the information you need is on a bus connected by a particular VI, check the
binary firmware documentation for your
it is recommended that you use the Ford Reference VI. It is most reliable platform.
The C5 devices are available to provide the specific new functionality.
There are two ways you can obtain a vehicle interface.
This image shows all of the available devices that are described below.
The VI is a open source reference design for a “dongle” style vehicle interface
that connects directly to the diagnostic port with no cable. Ford created this
design and manufactured a small quantity to seed the developer community. If you
have an idea for an OpenXC application and this hardware would help,
you can buy the hardware
The reference VI is not as compact as the C5 BT, but it is open
source hardware, so you are free to use or modify this design in your own
hardware, and it connects to both the CAN1 and CAN2-1 bus pins (and
with a small modification can connect to CAN2-2).
There are three types of Vehicle Interfaces made by CrossChasm that are available. They
are all similar and based off the same PIC32 platform. The first is a Bluetooth
Classic, the second is a 3G Cellular device, and latest is a Bluetooth LE device. See
the table below or
for more complete details.
All of the CrossChasm devices are available at the
CrossChasm C5 BT
The C5 BT is a very compact interface, so it’s great for fleet deployments. It
connects to the CAN1 bus pins only. A crossover
cable is needed to access a secondary CAN bus.
CrossChasm C5 Cellular
The C5 Cellular device allows a direct GSM connection with a user supplied SIM card. The
device also has