Omron C200HW-CORT21-V1 Operation Manual page 20

Device description
OSI model
ISO 11898
Profiles
The model is according the ISO Open Systems Interconnection (OSI)
reference model. Of this seven-layer model, only three are applicable for a
CANopen device (the physical layer, the data link layer and the application
layer).
The data link layer and a part of the physical layer are described in ISO
11898, and are usually implemented in silicon (CAN controller).
CANopen provides a standardised application layer and communication
profile. The optional framework for programmable devices specifies
additional communication functionality. In addition, CANopen specifies bit-
timing and recommends pin-assignments for several types of connector.
The standardised device profiles, interface profiles, and application profiles
describe the default behaviour and the optional functionality of devices,
interfaces, and applications.
The interaction between devices at the three ISO layers is depicted below.
At the application layer, the interaction involves the accessing of objects via
an index numbering system. Refer to section 1-2-2-1 for more details about
objects and indexing.
At the data link layer, these object accesses are translated to CAN message
frames with certain identifiers and data blocks. The maximum number of data
bytes per CAN frame is eight, therefore accesses to larger-sized objects in
the device are fragmented over more than one frame.
At the CAN physical layer, the CAN frames are translated to bus signal levels
and vice versa.
Section 1-2
3