Drive User Guide
15
4. Communication Architecture of EtherCAT Drive
The figure shown below indicates the architecture of CoE(CANopen over EtherCAT) drive network
module. It can be separated to data link layer and application layer. Data link layer is used to manage the
transmission interface of data between the master and salve station. Application layer is used to
implement the function of state transition compatible between CiA402 (CANopen Drive Communication
Protocol) and EtherCAT.
There are two types of data transition mode between the application layer and data link layer: time
critical and non-time-critical data transition. Data of time critical indicates that the data transition has to
complete within a specific time. If not, it may cause the control failure. The data of time critical is
normally used in the periodic communication. It is called as cyclic process data communication. However,
the data of non-time-critical is able to complete by using the non-periodic communication i.e. use
non-periodic mailbox communication.
The process data object (PDO) in the application layer are consisted of the objects which can be
mapping to PDO and the contents of process data defined in the PDO mapping; and process the read and
write data through the periodic process data communication. However, the service data object (SDO) is
to read and write the data in the object dictionary through the mailbox data communication.
The chart shown below indicates the layout between the process data of data link layer and the
SyncManager of mailbox data communication:
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