Add_Time_To_Date
C14B_ADD_TIME
COPF_Determine_Duration
RP_Calc_Date_In_Interval
SWI_Duration_Determine

DATA: L_OUT_DATE LIKE SY-DATUM.

CALL FUNCTION 'ADD_TIME_TO_DATE'
EXPORTING
   I_IDATE = sy-datum
   I_TIME = 20
   I_IPRKZ = '' " ''=Day, 1=Week, 2=Month ,3 = Year
IMPORTING
   O_IDATE = L_OUT_DATE
EXCEPTIONS
   INVALID_PERIOD = 01
   INVALID_ROUND_UP_RULE = 02
   INTERNAL_ERROR = 03 .

write: / L_OUT_DATE.

IF SY-SUBRC <> 0.
   EXIT.
ENDIF.

DATA: L_OUT_DATE LIKE sy-datum,
          L_OUT_TIME LIKE sy-uzeit,
DATA: l_time TYPE sy-uzeit.

l_time = '050000'.

CALL FUNCTION 'C14B_ADD_TIME'
        EXPORTING
              I_STARTTIME  = SY-UZEIT
              I_STARTDATE = SY-DATUM
              I_ADDTIME     = l_time
        IMPORTING
              E_ENDTIME  = L_OUT_TIME
              E_ENDDATE = L_OUT_DATE
        EXCEPTIONS
              OTHERS = 1.