TCODE：OB08
CALL FUNCTION 'READ_EXCHANGE_RATE'
EXPORTING
* CLIENT = SY-MANDT
DATE = '201801101'
FOREIGN_CURRENCY = 'USD'
LOCAL_CURRENCY = 'SGD'
TYPE_OF_RATE = 'L'
* EXACT_DATE = ' '
IMPORTING
EXCHANGE_RATE = l_rate.