AMT58x-CB CANopen®
18
6.3 Communication objects
Four different kinds of communication messages are used in a
CANopen® network:
Network management NMT protocol: NMT protocols are used to
issue state machine change commands (i.e. to start and stop the
devices), detect remote device boot-ups and error conditions.
Process Data Objects PDO protocol: used to process real time
data (transmission of process data in real time).
Service Data Objects SDO protocol: used to set and read values
from the object dictionary of a remote device.
Special Function Objects:
- SYNC: synchronization message used by master to enable
slaves devices to transmit process data (encoder position and
velocity).
- Emergency: error messages are triggered by each error event.
- Nodeguard: used to request the state of the slave.
Relation between device states and communication objects:
Initial. Pre-oper.
Operat. Stopped
NMT X X X
PDO X
SDO X X
SYNC X
EMCY X X
Boot-up X
Node guard
X
X
X
6.3.1 Pre-defined connection set
Master
Slave broadcast
Type of COB
(Object)
Function code
(binary)
COB-ID (hex)
NMT 0000 000
SYNC 0001 080
peer-to-peer transmission
EMERGENCY
0001
081 - 0FF
PDO 1 (tx)
0011
181 - 1FF
PDO 2 (tx)
0101
281 - 2FF
PDO 3 (tx)
0111
381 - 3FF
PDO4 (tx)
1001
481 - 4FF
SDO (tx)
1011
581 - 5FF
SDO (rx)
1100
601 - 67F
Node guard
1110
701 - 77F
Boot-up
1110
701 - 77F
The type of COB (tx or rx) is viewed from the slave device.
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