AMT58x-EC EtherCAT®
43
6.2.2 Communication messages
EtherCAT Datagram of CoE mode has the following structure:
Mbx Header
CoE Cmd
Cmd specific
data
type = 3
Numb
er
res
Typ
e
6 bytes
9 bits
3 bits
3
bits
0 … 1478
bytes
Mbx Header
= 3
CoE mode
Number
= 0 in case of SDO messages
≠
0 in case of PDO messages, it defines the type of
service
res reserved
bits
Type =
0
reserved
= 1 Emergency message
= 2 SDO request
= 3 SDO response
= 4 Transmitted PDO (TxPDO)
= 5 Received PDO (RxPDO)
= 6 Remote transmission request of TxPDO
= 7 Remote transmission request of RxPDO
= 8 SDO information
= 9 … 15 reserved
Cmd specific data PDO messages: are the process data, e.g.
position value
SDO messages: standard CANopen frame
Transmit (tx) or receive (rx) “Type” is viewed from Slave.
6.2.3 Process Data Objects (PDO)
PDO messages are used for transmitting or receiving process data in
real time; data to be transmitted or received is defined in PDO
Mapping and managed by Sync Manager PDO Mapping.
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