Hi Anil,
You can also the function module FMDT_READ_MD_WBS_ELEMENT Read WBS Element Master Data with the external version of the WBS Element ID i.e. PRPS-POSID.
Source Field should be POSID and Target Field should be MEASURE on the row for POSID. Also note that the "." in the mask will be dropped so calculate the digits accordingly.
Thanks
Shyam