Hi Mankaran,
Thanks for posting your own answer :-)
Yes, you can add SDOs to the ETherCAT configuration. If you change the value in Desk or via the Motorcortex API the value of a SDO gets sent via mailbox to the slave. If you want to read all configured SDOs you need to trigger a read event by writing a "1" to root/Ethercat/read_sdos. All SDOs will then be updated in the tree.
It is not recommended to cyclically read or write SDOs, since the mailbox messages may affect the normal cyclic communication (PDOs) via etherCAT.
Configured SDOs can also be added to the GUI (via the GRID editor) so you can conveniently read or change the values from a GUI.
Some drive manufacturers allow configuring SDOs as PDOs (Synapticon allows alld SDOs to be mapped as PDO), so you can update them cyclically. We have used that feature to adjust control gains on the drive cyclically and do gain scheduling on the master.
I hope this also inspires to look at different solutions for your challenges.