In the language of the CAN standard, all messages are referred to as frames, such as data frames, remote frames, error frames, etc. Information sent to the CAN bus must be compliant to defined format frames of different but limited length.
Any node connected to the network may transmit a new frame as soon as the bus is idle. The consistency of a frame must be simultaneously accepted by all nodes in a CAN network.
CAN provides four different types of message frames:
- Data Frame – Sends data
Data transfer from one sending node to one or numerous receiving nodes.
- Remote Frame – Requests data
Any node may request data from another source node. A remote frame is consequently followed by a data frame containing the requested data.
- Error Frame – Reports error condition
Any bus participant, sender or receiver, may signal an error condition at any time during a data or remote frame transmission.
- Overload Frame – Reports node overload
A node can request a delay between two data or remote frames, meaning the overload frame can only occur between data or remote frame transmissions.