12 (136)
<CoE SdoInfo="1" CompleteAccess="1" PdoAssign="0" PdoConfig="0"
PdoUpload="1"/>
<FoE/>
</Mailbox>
3.2
EtherCAT Implementation Details
3.2.1
General Information
The module implements a full EtherCAT slave with the following basic properties:
Application Layer:
CANopen over EtherCAT
FMMUs.
4
Sync Managers.
4
RAM Size:
16 kByte
See also...
•
CANopen over EtherCAT Implementation Details, p. 14
3.2.2
EtherCAT Synchronization
EtherCAT synchronization and jitter accuracy may depend on different things:
•
How often the master sends out sync frames
•
Temperature variations in the environment (large impact)
•
The implementation of the EtherCAT slave device
•
Which Ethernet physical layer is used in the slave devices (RJ45, E-Bus etc.)
The Anybus CompactCom 40 EtherCAT modules all demonstrate less than 1 μs synchroniza-
tion accuracy. For RJ45 products the accuracy may be around 50 ns under good conditions,
and for E-Bus products around 30 ns.
3.2.3
Sync Managers
The module features four Sync Managers:
Sync Manager 0
Used for mailbox write transfers (Master to Slave).
The module has a configurable write mailbox size with default size of 276 bytes,
corresponding to 255 bytes plus relevant protocol headers and padding.
Sync Manager 1
Used for mailbox read transfers (Slave to Master).
The module has a configurable read mailbox size with default size of 276 bytes,
corresponding to 255 bytes plus relevant protocol headers and padding.
Sync Manager 2
Contains the RxPDOs (in practice, Sync Manager 2 holds the Read Process
Data).
Sync Manager 3
Contains the TxPDOs (in practice, Sync Manager 3 holds the Write Process Data).
3.2.4
FMMUs
There are four FMMUs. The EtherCAT master can use the FMMUs freely for any purpose.
Anybus
®
CompactCom
™
40 EtherCAT
®
Network Guide
SCM-1202-034 1.1