Have you ever wondered how your car is following command to perform any task? How all the sensors, warning lights, control modules of your car are communicating with each other to give you a flawless beautiful ride. 
Behind this, lots of things are going on to provide a proper channel to communicate with each other.


In early days, gauzes, modules and warning lights were simply connected directly to sensors. Due to this, there is an addition of a large number of sensors is employed which results in a large number of cables to
connect with each other to communicate. Such interconnections between them
make it complex. And it also adds up the considerable weight to car or
vehicle.
So to cope up with his problem a new communication protocol comes in the image as CAN
Protocol.





CAN (Controller Area Network)

CAN (Controller Area Network) is a serial communication BUS system which is designed for robust and flexible performance in harsh conditions particularly for industrial application.
CAN was first developed by Robert Bosch in 1982.
CAN communication is widely used in the automobile industry, drones and industrial automation. This protocol simplifies the monitoring and diagnosis of detected faults.

In the earlier time, there was a lesser number of sensors and modules in the car. Point to point connections used to make with hard wire for communication because they did not need to be linked together for exchanging real-time information.
But in today’s era, there are strict norms for environmental regulations and emission norms. Such circumstances require to have more modules, sensor and also, they have to share information in real-time.

CAN allows various modules to communicate with each other in a common cable. ‘All ECUs communicate effectively without a central Computer.’
CAN communication can be done by only 2 hard wires. Wires are twisted pair cables with bus length 40 m and the maximum node would be 30 nodes with terminal resistance of 120 ohms.

Generally, CAN cable consist of 2 twisted hard wires with a metallic mesh as a covering.

Yellow Colour wire = CAN High Wire - (1)
Green Colour wire = CAN Low Wire - (0)

Metallic mesh as a covering on wires is provided to reduce noise occurring in the communication channel.
CAN Signal is a differential Signal. Current flowing in each is same but opposite in direction which results in field cancellation effect due to which there is a low noise emission. This ensures low noise and a high rate of transmission over wires.

In Automobiles, we generally use two types of CAN bus protocol.

  • 1   High Speed CAN
  • 2   Low Speed / Fault-Tolerant CAN

  • High Speed CAN

ISO 11898-2 High Speed CAN
In Automobile Industry, the most widely CAN system used is High Speed CAN (ISO 11898-2).
It allows speed up to 1 MBPS and use a linear bus with termination resistance of 120 Ohms at both ends.

  • Low Speed / Fault-Tolerant CAN

In Low-Speed CAN (ISO 11898-3), the termination resistors are located at each module and overall resistance is around 100 ohms. On having terminal resistance at each module, it can also communicate in case of wire failure.
The transfer rate is around 40 Kbps to 125 Kbps.

 CAN Bus Connector

CAN Communication is accessed by OBD (On Board Diagnostic) Port. OBD is the vehicle’s diagnostic and reporting system. This is the same port which is used for troubleshooting error codes and for software updates.

On occurring problems in CAN communication channel, DTC (Diagnostic Trouble Codes) arises as “U” trouble codes with the illumination of Check Engine Light of vehicle.
We can check the proper functionality of parts of the vehicle by plugging in the Diagnostic Tool of that particular part. For example, We can use diagnostic tool for Engine, Transfer Case, Transmission, ABS (Antilock Braking System).
OBD is 16 pin connector. Generally, Pin number 4 & 5 is kept ground, pin number 6 & 14 is used as diagnostic socket and pin number 16 is kept 12 Volt supply.

 Advantages of CAN:

  •        LOW COST

On using CAN protocol, all modules, sensors communicate through via a single CAN Bus. It eliminates all other hard wires which result in the reduction of cost as well as the considerable weight of the vehicle. It also reduces faults and errors.

  •        CENTRALIZED

As all sensors and modules are connected through a single wire so it provides a central way to detect faults across all the modules and sensors present in the car.

  •        ROBUST

Having protection against Electromagnetic Interference makes it robust and fully functional without any noise or interference in the communication channel.

  •        FLEXIBLE

We can easily add or remove any module without hampering of communication between other peripherals and can easily modify & update their software.

  •        EFFICIENT

CAN messages are prioritized via IDs so that the highest priority ID is non-interrupted.


In today's era, CAN is widely using in Automative industry, Drone technology and in the automation industry.CAN is a central controller that monitors all the car’s system and sensors. In other words, it's a nervous system of a vehicle.