Appendix C CANopen Protocol
C
The CANopen Communication Object
The CANopen communication protocol contains PDO, SDO, NMT and other predefined CANopen
communication object.
Refer to section C.3 for PDO introduction.
Refer to section C.4 for SDO introduction.
Refer to section C.2 for NMT introduction.
Other predefined CANopen communication objects (SYNC and EMCY)
SYNC Object (Synchronous object)
The synchronous object is the message broadcasted periodically by the master node in the
CANopen network. This object is used to realize the network clock signal. Every device decides
whether to use the event and undertake the synchronous communication with other network
devices according to its configuration. For example, when controlling the driving device, the
devices do not act immediately after they receive the command sent by the master. They do act
until they receive the synchronous message. In this way, many devices can act synchronously.
The format of the SYNC message:
COB-ID
80（hex）
Emergency Object
The emergency object is used by the CANopen device to indicate an internal error. When an
emergency error occurs in the device, the device sent the emergency message (including the
emergency error code), and the device enters the error state. After the error is eliminated, the
device sends the emergency message, the emergency error code is 0, and the device enters
the normal state.
The format of the emergency message:
COB-ID Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7
80（hex）
+Node-ID
Error
register
Factory-defined error code
LSB MSB
Note:
The value in the error register is mapped to index 1001 (hex) in the object dictionary. If the value
is 0, no error occurs. If the value is 1, a general error occurs. If the value is H’80, an internal
error occurs in the device.
C-3
To Next Page
Loading...
Need help?
General
