Filter
Top Products
24 Fieldbus interface
3 Basics IL•1F CANopen DS301
0198441113586, V2.01, 11.2008
Example Selection of a COB ID
For a device with the node address 5, the COB ID of the communication
object T_PDO1 is:
384+node ID = 384 (180
h
) + 5 = 389 (185
h
).
Data frame The data frame of the CANopen message can hold up to 8 bytes of data.
In addition to the data frame for SDOs and PDOs, special frame types
are specified in the CANopen profile:
• Error data frame
• Remote data frame for requesting a message
The data frames contain the respective communication objects.
3.2.3 Communication relationships
CANopen uses 3 relationships for communication between network de-
vices:
• Master-slave relationship
• Client-server relationship
• Producer-consumer relationship
Master-slave relationship A network master controls the message traffic. A slave only responds
when it is addressed by the master.
The master-slave relationship is used with network management ob-
jects for a controlled network start and to monitor the connection of de-
vices.
Figure 3.7 Master - slave relationships
Messages can be interchanged with and without confirmation. If the
master sends an unconfirmed CAN message, it can be received by a
single or by several slaves or by no slave.
To confirm the message, the master requests a message from a specific
slave, which then responds with the desired data.
data
Slave
Slave
Slave
data
Slave
request
Master
Master