[etherlab-users] Sync manager and datagram react

[martin troxler]

Hi 

>When reading the EtherCAT Master documentation about FMMU, I meet this sentence: "In order to >make a sync manager react on a datagram accessing its memory, it is necessary to access the last byte >covered by the sync manager." 

>I do not understand: which access to the last byte? Whose last byte? The last byte in the datagram? or EtherCAT frame?
The byte on the last address within the mailbox address range (see configured mailbox size) 

>How can sync manager identify its datagram by just the last byte?
By comparing the given address and the size of the transferred data.  A master must either write the full size of the mailbox (even if the real payload is much smaller) or it has to write 2 datagrams: One with the real payload, addressed to the start of the mailbox, and an additional datagram that writes just one byte at the end of the mailbox address range.
 
Regards, 
Martin


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Thank You.
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