Data transfer
Structure of the CAN telegram
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EDSMF2178IB EN 3.0
Identifier (COB−ID)
The principle of the CAN communication is based on a message−oriented data exchange
between a transmitter and various receivers. Here, all nodes can quasi simultaneously
transmit and receive messages. In case of CANopen, a node orientation is achieved by
having only one transmitter for each message.
The control which node is to receive a transmitted message is executed via the identifierin
the CAN telegram, also called COB−ID(Communication Object Identifier). In addition to the
addressing, the identifier contains information on the priority of the message and the type
of user data.
With the exception of the network management and the sync telegram, the identifier
consists of a basic identifier and the node address of the node to be addressed:
Identifier (COB−ID) = basic identifier + adjustable node address (Node−ID)
The identifier assignment is defined in the CANopen protocol.
Basic identifier
The basic identifier is preset as default with the following values according to the CANopen
specification:
Object
Direction Basic identifier
from the drive to the drive dec hex
NMT 0 0x000
Sync 128 0x080
Emergency X 128 0x080
PDO1
(Process data channel 1)
TPDO1
X 384 0x180
RPDO1
X 512 0x200
PDO2
(Process data channel 2)
TPDO2
X 640 0x280
RPDO2
X 768 0x300
PDO3
(process data channel 3)
TPDO3
X 896 0x380
RPDO3
X 1024 0x400
SDO1
(Parameter data channel 1)
X 1408 0x580
X 1536 0x600
SDO2
(parameter data channel 2)
Lenze setting: not active.
X 1472 0x5C0
X 1600 0x640
Node guarding / heartbeat X 1792 0x700
Node address (node ID)
Each node of the CAN network must be assigned with a node address (also called node ID)
within the valid address range for unambiguous identification.
ƒ A node address must not be assigned more than once within a network.
ƒ The node address of the controller is configured under code C1850/C2350 or via DIP
switch(^ 33).
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