Hi Arun,
If you mention recordset structure as Header,1,Detail,*,Footer,1 then entire file contains only one record set structure so the entire file will come as one message, You can mention the Recordsset structure as Detail,1 and give Recordsets per message as per your requirement then file adapter will split the file into multiple messages, check below FCC configurations.
In the mapping you can apply below logic to your Detail node then Header and Footer records are not part of target message.
Regards,
Praveen.