Hello Dinesh ,
As i understand , you want to debug the smartform to see the incoming data to the form.
For that you need to put an external break point inside the Method (eg. PPF~Execute).
Next you find the Call Function(put external break point) which will call the PPF action.
Inside the call function you can serach the FM which calls the smartform ( e.g. SSF_FUNCTION_MODULE_NAME) .
Next , while debugging you can give the formname of yours and can go inside your smartform.
Let me know if you need more help for the same.
Thanks
Romit Raina