Festo EMCA-EC-67 CO Series, Description

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3 EtherCAT with FHPP
64 Festo – EMCA-EC-C-HP-EN – 2017-11e – English
3.8.3 SDO Write command (SDO download)
O write command, the controller can access parameter data (Value) in the CoE object directory in the
EMCA acyclically and can write to them. Every request is confirmed by the EMCA with an acknowledge­
ment.
Controllers EMCA
SDO download/Download SDO ... request
(SDO write command)
Request
Acknowledgment
SDO download/Download SDO ... response
CoE OD
Object
Value
Fig. 3.9 Access procedure: Writing to parameter data
The SDO service supports the following SDO write commands:
SDO Service Description
SDO download expedited request Writing to
parameter
data (down­
load)
1 … 4 bytes of us­
age data (expedi­
ted)
Request (request)
SDO download expedited response Acknowledgement (re­
sponse)
SDO download normal request 5 … 1,406 bytes of
usage data (nor­
mal)
Request (request)
SDO download normal response Acknowledgement (re­
sponse)
Download SDO segmented request 1,407 … n bytes of
usage data
1)
(seg­
mented)
Request (request)
Download SDO segmented response Acknowledgement (re­
sponse)
1) The usage data are fragmented into packages, each of max. 7 bytes.
Tab. 3.44 SDO Services: Writing to parameter data
Note
Dispense with SDO write commands (Download ... request) that refer to the objects
mapped into the PDO because the corresponding parameter data are otherwise over­
written alternately in a chronologically undefined sequence by the transmitted process
data objects (PDO) and service data objects (SDO).
Note
Acknowledgement (download ... response) of the EMCA must be waited for in any event!
The next SDO request cannot be transmitted until the EMCA has acknowledged the
write command.