User`s manual

IA261/262 WinCE User’s Manual CANopen Library
B-3
The protocol is designed in three levels, as shown in Figure 1. The lowest level is the CANbus
driver providing hardware abstracted CAN support. The communications management level is the
primary interface between the driver and the individual endpoint handling. Besides the application,
there is also the dictionary. In essence, it resides outside of the communication object, and is
directly connected to the SDO endpoint.
The CANopen specification defines several possible endpoints. The five endpoint objects listed
below are implemented in this protocol; others may be made available in the future.
• The Server SDO
• Four Static PDOs
• Synchronization Consumer
• Network Management Slave
• Node Guard or Heartbeat
SERVER SDO COMMUNICATION
The default server SDO (Service Data Object) is provided. The SDO communications path is
directly linked to the object dictionary; SDO messages contain information that relates the SDO to
a particular object. Data in every message is decoded, validated, and (if valid) eventually executed.
There are essentially two basic operations: read and write. Thus each complete SDO transfer
(which may be multiple messages) will either read or write a single object referenced in the
dictionary.