SFA-5000 • SFA-10000 EtherCAT
are sent to the local micro-controller so that it is able to synchronize its own
clock to Slaves clock.
Sync Manager
Sync Manager has the task of synchronizing data transfer between the Master
and the Slave and prevents the same memory area from being written by
different events.
There are two synchronization modes:
3-Buffer Mode;
1-Buffer Mode.
The synchronisation mode is initialized through the XML file or by loading data
directly from EEPROM (SII).
Buffered Mode (3-Buffer Mode)
In this mode new data can be accessed at any time by both the EtherCAT Master
and the ESC controllers; no timing restrictions are imposed.
Three buffers are necessary (three consecutive memory areas); one buffer is
always available to the ESC controller for writing and one buffer always
contains updated data to be read by the Master.
The buffered mode is typically used for cyclic data exchange, i.e. process data.
Mailbox Mode (1-Buffer Mode)
In this mode a “handshake” between the Master and the Slave must be used; in
fact one only memory buffer is available to both the Master and the Slave for
writing and reading; the Master (or the Slave) is enabled to write only when the
buffer is empty, that is when the Slave (or the Master) has finished reading the
data buffer. And vice versa: the Master (or the Slave) is enabled to read only
when the buffer is empty, that is when the Slave (or the Master) has finished
writing the data buffer. The mailbox mode is typically used for application layer
protocols and exchange of acyclic data (e.g. parameter settings).
The draw-wire encoder features four Sync Managers, see the
•
Sync Manager 0 (SM MailBox Receive, SM0)
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 (SM MailBox Send, SM1)
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 (SM PDO output, SM2)
It contains the RxPDOs (i.e., Sync Manager 2 holds the Read Process
Data).
•
Sync Manager 3 (SM PDO input, SM3)
MAN SFA_5000_10000_EC E 1.0.odt
6 - EtherCAT® interface
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