CAN
The CAN protocol is an international standard defined in ISO
11898. The conformance test for the CAN protocol is defined
in ISO 16845, which guarantees the interchangeability of CAN
chips.
CAN relies on a "broadcast communication mechanism",
which is based on a message-oriented transmission protocol.
It defines message contents rather than stations and station
addresses. Every message has a message identifier, which
is unique within the whole network since it defines content
and the priority of the message. This is important when
several stations compete for bus access.
However, identifiers can be added to an existing network
only by changing the sender and relevant receivers, but
the message timing changes for all nodes. No composability
features that guarantee that system extensions or modifications
do not require a system-wide re-testing are possible at
the communication level.
Arbitration between concurrent messages is non-destructive
and efficient, but it limits the bit rate (< 1 Mbit/s)
and the topology (no star or ring, no repeaters). Arbitration
is therefore not suited for safety-critical applications.
For more information on CAN please refer to
the CiA
website.
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