Puedes utilizar la función READ_TEXT_INLINE, te agrego un ejemplo.
TYPES: it_lin LIKE tline.
DATA: it_lines TYPE TABLE OF it_lin,
it_inline TYPE TABLE OF it_lin,
line TYPE it_lin.
DATA: lf_matnr LIKE mara-matnr,
lf_matnr_tmp LIKE thead-tdname.
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
EXPORTING
input = i_datos-matnr
IMPORTING
output = lf_matnr.
MOVE lf_matnr TO lf_matnr_tmp.
IF p_langu IS INITIAL.
p_langu = 'S'.
ENDIF.
CALL FUNCTION 'READ_TEXT_INLINE'
EXPORTING
id = 'GRUN'
inline_count = 1
language = p_langu
name = lf_matnr_tmp
object = 'MATERIAL'
TABLES
inlines = it_inline
lines = it_lines
EXCEPTIONS
id = 1
language = 2
name = 3
not_found = 4
object = 5
reference_check = 6
OTHERS = 7.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
* READ TABLE it_lines INTO line INDEX 1.
LOOP AT it_lines INTO line.
CONCATENATE i_datos-txt_datos_basicos line-tdline
INTO i_datos-txt_datos_basicos SEPARATED BY space.
ENDLOOP.
