Questions tagged [can-bus]

The CAN bus is a serial bus that allows multiple masters and uses a broadcast model. A message start with an ID, can contain up to eight data bytes (64 data bytes for CAN FD) and uses non-return-to-zero encoding. Each node can receive, but only one can send at each point in time. It uses CSMA/CA algorithm for bus access. The lower the (numerical) ID, the higher the priority. Short networks (below 40 m) can achieve bit rates up to 1 Mbit/s.

A distinguishing feature of CAN is that when two nodes with different message identifiers attempt to transmit at the same time, there are no collisions (CSMA/CA). The higher priority message will go through without any need for the sender to re-transmit it. This ensures that a CAN system can never get into a live lock state in which two nodes would continually re-send the same two messages, and continually collide with each other.

A newer version/generation called CAN FD was recently developed. It supports higher clocking of the data portion of the message, allowing up to 64 bytes of payload.

Tag usage:

• Use this tag for all questions related to CAN or CAN FD software/firmware: drivers, controllers, communication, frames etc. Please note that hardware questions are off-topic and should be asked at https://electronics.stackexchange.com instead.
• It is recommended to combine the tag with embedded, to draw more attention to the question from the right kind of people.
• If you are using a particular programming language (say, c), you should add that tag as well.
• If the question is about higher layer protocols such as CANopen, J1939 or DeviceNet, the tag should be combined with the applicable higher layer protocol tag.

Links:

• Old CAN v2 specification
• Common pinouts
• Wikipedia
• CAN in Automation (CiA), non-profit organization that maintains the CANopen standard, among other things. Source for technical articles and standards.