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EPC-CM3 User Manual
Chapter 5 Overview of CANopen
largest space occupied by OD is 64K* 256 * 4 = 64MBYTES in theory.
COB - ID includes the FUNCTION segment and address segment (the NODE ID), and 127
stations can be defined in all. These stations are integrated in all kind of communication
messages with the COB ID values as the contents, and the IDs of the CANopen
communication messages can be expressed in the following formula.
COB-ID = FUNCTION+NODE-ID
The Node-ID shall be defined by the system integrators, for example, it can be set via the
toggle switch. The scope of Node - ID is 1 ~ 127(“0” is not permitted to be used). On the master
station, the function segment refers to the operation contents of the master station over the
slave station; the address segment (Node ID) the address of the slave stations operated
(station number); on the slave station, the function section shows the response of the slave
station to the master station, while the address segment refers to the address of the response
slave station (station number). Four types of communication messages are assigned by COB ID as specified in the CANopen communication models, and its scope is 000 h ~ 7 FFH. The
lower the value is, the higher the priority will be.
ID10
ID7
ID6
ID0
Function
Node-ID (1~127 sites)
Fig. 5-2 Composition of COB-ID
The COB-IB definitions for the broadcast objects of master/slave connected subnetwork
predefined by CANopen and its equal objects are as shown in Table 5-1 and Table 5-2.
Table 5-1 Broadcast Objects of Master/Slave Connected Subnetwork Predefined by CANopen
Broadcast Objects of Master/Slave Connected Subnetwork Predefined by CANopen
Function Code
Index of Communication
Object
COB-ID
（ID bits10~7）
Parameters in OD
NMT
0000
000H
SYNC
0001
080H
1005H,1006H,1007H
TIME SSTAMP
0010
100H
1012H,1013H
7