Structure Of Can Application Protocol Over Ethercat (Coe) - Omron SYSMAC FH Series User Manual

2 Methods for Connecting and Communicating with External Devices
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Structure of CAN Application Protocol over EtherCAT (CoE)

EtherCAT allows the use of multiple protocols for communication. EtherCAT slave terminal adopts
CAN application protocol over EtherCAT (CoE) as a device profile for CAN application protocol which
is one of the open network standards, which provides the communication interface to apply to Ether-
CAT devices.
The following figure indicates the CoE structure in the EtherCAT coupler unit.
FH Sensor Controller
Application layer
FH Unit application
2
Object dictionary
Transitions of
SDO (mailbox)
PDO mappings
communications
PDO communications (cyclic)
states
Registers Mailbox
Process data
SyncManager FMMU
EtherCAT data link layer
EtherCAT physical layer
The object dictionary for the CAN application protocol is roughly classified into PDOs (process data
objects) and SDOs (service data objects).
PDOs consist of the mappable object dictionaries, and the contents in process data are defined by the
PDO mappings. PDOs are used for PDO communications to exchange process data periodically.
Moreover, SDOs can read and write all object dictionaries and are used for non-periodic SDO (event-
driven message) communications.
In EtherCAT, by setting the object dictionaries for PDOs and SDOs using the CoE interface, EtherCAT
devices that have the same device profiles as the CAN application protocol can be provided.
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FH/FHV Series Vision System User's manual for Communication Settings (Z342-E1)