CAN Protocol Interview Questions

The CAN protocol stands for controller area network protocol that is used for communication between electronic devices embedded in a vehicle.

The major features of CAN Protocol are:

• Low Cost
• Speed
• Flexibility
• Robustness
• Built-in Error Detection.

Some of the applications of CAN Bus are:

• Pedelecs
• Building automation.
• Elevators, escalators.
• Agricultural equipment.
• Industrial automation and mechanical control.
• Electronic equipment for aviation and navigation.
• Passenger vehicles, trucks, buses.

CAN messages are configured in two formats that are the standard or base frame format supports a length of 11 bits for the identifier and the extended frame format supports a length of 29 bits for the identifier. CAN Messages or Frames are of four types:

• Data frame
• Remote frame
• Error frame
• Overload frame

High Speed CAN offer baud rates from 40 Kbit/s to 1 Mbit/sec i.e. it can support maximum data rate up to 1 Mbit/sec.

Low Speed CAN is also known as Fault Tolerant CAN offers baud rates from 40 Kbit/s to 125 Kbits/sec.

Standard CAN and Extended CAN are the two formats in which CAN messages or frames are configured. The standard CAN format supports a length of 11 bits for the identifier while the extended CAN format supports a length of 29 bits for the identifier.

The Can Arbitration is the process in which two or more CAN controllers agree on who is going to use the bus.

SAE J1939 is a set of standards defined by SAE. SAE J1939is built on CAN which is used in heavy-duty vehicles such as trucks and buses, mobile hydraulics, etc.

ISO 11898 is the standard for CAN. It is categorized into two parts:
ISO 11898-1: It covers the data link layer
ISO 11898-2: It covers the CAN physical layer for high-speed CAN.

CANopen is a high-level communication protocol and device profile specification that is used for embedded networking applications, such as in-vehicle networks.