Festo CMMT-ST-SW, Original Instructions Manual

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11.8.1 SDO communication
SDO communication supports the following SDO services:
–
SDO read command (SDO upload/Upload SDO): acyclic reading of parameter data
è 11.8.1.2 SDO read command (SDO upload/upload SDO)
– SDO write command (SDO download/Download SDO): acyclic writing to parameter data
è 11.8.1.1 SDO write command (SDO download/download SDO)
– SDO error transmission: event-controlled transmission of SDO error code
è 11.8.1.3 SDO error message (Abort SDO transfer request)
11.8.1.1 SDO write command (SDO download/download SDO)
Via the SDO write command (SDO write command) the controller (Controller) can acyclically access the
CoE object directory CoE OD in the CMMT to write the data of an object (Value). After processing the
write command, the CMMT sends an acknowledgement (Acknowledgment) to the controller.
Controller CMMT
SDO download/Download SDO ... request
(SDO write command)
Request
Acknowledgment
SDO ownload/Download SDO ... response
CoE OD
Object
Value
Fig. 115 Write access to object data
The SDO service supports the following SDO write commands:
SDO service Description
SDO download expedited request Write command request for 1
…
4 bytes user data
SDO download expedited response Write command acknowledgement with 1
…
4 bytes user
data
SDO download normal request Write command request for 5
…
1,406 bytes user data
SDO download normal response Write command acknowledgement with 5
…
1,406 bytes
user data
Download SDO segmented request Write command request for 1,407
…
n bytes user data
Download SDO segmented response Write command acknowledgement with 1,407
…
n bytes
user data
Tab. 471 Supported SDO read commands
NOTICE!
The controller must not send the next request (request) until the acknowledgement of the write com-
mand (download … response) has been received by the controller.
EtherCAT
537 Festo — CMMT-ST-SW — 2019-02