Via system bus (CAN)
Identifier
8
Networking via system bus (CAN)
8.1
8.1.2
L
8.1−2
EDSPM−TXXX−9.0−11/2009
8.1.2 Identifier
The principle of CAN communication is based on a message−oriented data
exchange between a transmitter and many receivers. Therefore, all nodes can
transmit and receive more or less at the same time.
The so−called identifier in the CAN telegram, also called COB−ID (Communication
Object Identifier), controls which node is to receive a transmitted message. In
addition to the addressing, the identifier contains information on the priority of the
message and the type of user data.
The identifier consists of a ’basic identifier’ and the node address of the device to
be approached:
Identifier = Basic identifier + node address
l This node address is set with the coding switch at the module:
– Modular system: At CAN gateway
– Compact system: At each module
l Network management and sync telegram only require the basic identifier.
l The identifiers can also be set individually. ( 8.3−3)
8.1.3 Saving changes
) Note!
l Changes of the baud rate, node address, identifiers for PDOs,
and the transmission mode for PDOs must be saved with
I2003
h
= 1, for being maintained even after switching off the
supply voltage.
l Any changes will become effective only after a Reset Node:
– Switch the supply voltage on again
– Execute NMT command "81
h
" (see chapter "Network
management (NMT)")
– Set I2358
h
= 1
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