CAN® stands for Controller Area Network. It was developed originally as a robust message-based protocol for use in automotive applications. It has spread to other uses as well and is now found in medical equipment and industrial controls. FiX is an acronym for Flight information eXchange. It is a set of protocol specifications for exchanging information between aircraft avionics and flight systems. This specification and the protocols themselves are licensed under a Creative Commons license that allows anyone to modify and redistribute these documents without charge.

The full specification can be found on the MakerPlane GitHub site here: https://github.com/makerplane/canfix-spec

This is a community supported endeavor, with the primary goal of providing a standard method for avionics and flight control systems to communicate with one other in a vendor neutral way.
The specifications and protocols are primarily geared toward the Experimental Amateur Built (EA-B) aircraft community. Keeping the specification open and free allows airplane builders to create their own devices and write their own software that will be able to communicate with other devices without need to pay for specifications or licenses. It also encourages collaboration in the development and improvement of the protocols themselves. We have incorporated support for electric propulsion for example and extended ADS-B and weather information.

CAN-FiX Gateway

The FiX Gateway application is a free open source program that abstracts flight information from the CAN-FiX protocol and allows communication between different technologies that may wish to implement CAN-FiX without changing their underlying code.  The primary use is as the interface to the pyEFIS electronic flight information project.  It can also be used to interface flight simulator software to ‘real’ hardware such as instrumentation or custom flight controls.

CAN-FiX Bus Connectors

The standard connector for CAN-BUS devices is a DB-9 and the network is terminated at each end with a 120 ohm resistor.   The standard connector wiring is shown in the image below.   Installers have the option of powering the module through the DB-9 connector or powering directly from the module to the avionics bus.  Typical installations would only require two wires (CAN_H and CAN_L) from the module to the CAN-FiX bus plus power.

 Standard DB-9 CAN connection pin-out.

MakerPlane Axis-9 DB-9 CAN hub.

Using the Connector Bus.