Hi,
You can use FM 'SAP_WAPI_START_WORKFLOW' to pass the valyes to WF attributes.
Create Attributes in WF level and pass values using input_container when you trigger WF.
CALL FUNCTION 'SAP_WAPI_START_WORKFLOW'
EXPORTING
task = task
language = language
do_commit = do_commit
START_ASYNCHRONOUS = l_ASYNCHRONOUS
IMPORTING
return_code = return_code
workitem_id = workitem_id
TABLES
input_container = input_container
message_lines = message_lines
message_struct = message_struct.
Regards,
Deepika.