Rainbow Electronics CAN интерфейс - Manual (Page 38)

BOSCH
ROBERT BOSCH GmbH, Postfach 300240, D-7000 Stuttgart 30
Sep. 1991
Part B - page 36
2 BASIC CONCEPTS
CAN has the following properties
• prioritization of messages
• guarantee of latency times
• configuration flexibility
• multicast reception with time synchronization
• system wide data consistency
• multimaster
• error detection and signalling
• automatic retransmission of corrupted messages as soon as the bus is idle again
• distinction between temporary errors and permanent failures of nodes and
autonomous switching off of defect nodes
Layered Architecture of CAN according to the OSI Reference Model
• The Physical Layer defines how signals are actually transmitted and therefore deals
with the description of Bit Timing, Bit Encoding, and Synchronization. Within this
specification the Driver/Receiver Characteristics of the Physical Layer are not
defined so as to allow transmission medium and signal level implementations to be
optimized for their application.
• The MAC sublayer represents the kernel of the CAN protocol. It presents messages
received from the LLC sublayer and accepts messages to be transmitted to the LLC
sublayer. The MAC sublayer is responsible for Message Framing, Arbitration,
Acknowledgment, Error Detection and Signalling. The MAC sublayer are supervised
by a management entity called Fault Confinement which is self-checking
mechanism for distinguishing short disturbances from permanent failures.
• The LLC sublayer is concerned with Message Filtering, Overload Notification and
Recovery Management.
Basic Concepts