Using Subrotine pool we can solve the issue.
Write the code in SAPScripts
/: PERFORM TEST IN PROGRAM ZTEST_XML
/: USING &T166A-TXNAM&
/: USING &T166A-TDOBJECT&
/: USING &T166A-TDID&
/: CHANGING &DES&
/: ENDPERFORM
* &DES&
*Create a Report
REPORT ztest_xml.
DATA: lv_name TYPE thead-tdname.
DATA ls_input TYPE itcsy.
DATA ls_output TYPE itcsy.
DATA : c_id TYPE thead-tdid,
c_object TYPE thead-tdobject,
lt_line TYPE TABLE OF tline,
ls_line TYPE tline.
*&---------------------------------------------------------------------*
*& Form TEST
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
* -->INPUT text
* -->OUTPUT text
*----------------------------------------------------------------------*
FORM test TABLES input STRUCTURE itcsy output STRUCTURE itcsy.
READ TABLE input INTO ls_input WITH KEY name = 'T166A-TXNAM'.
lv_name = ls_input-value.
READ TABLE input INTO ls_input WITH KEY name = 'T166A-TDID'.
c_id = ls_input-value.
READ TABLE input INTO ls_input WITH KEY name = 'T166A-TDOBJECT'.
c_object = ls_input-value.
* Get long text
CALL FUNCTION 'READ_TEXT'
EXPORTING
id = c_id
language = sy-langu
name = lv_name
object = c_object
TABLES
lines = lt_line
EXCEPTIONS
id = 1
language = 2
name = 3
not_found = 4
object = 5
reference_check = 6
wrong_access_to_archive = 7
OTHERS = 8.
DATA lv_long_text TYPE string.
LOOP AT lt_line INTO ls_line.
CONCATENATE ls_line-tdline lv_long_text INTO lv_long_text
SEPARATED BY space.
CLEAR ls_line.
ENDLOOP.
CONCATENATE 'Text you want:' lv_long_text INTO lv_long_text
SEPARATED BY space.
READ TABLE output INTO ls_output WITH KEY name = 'DES'.
IF sy-subrc = 0.
ls_output-value = lv_long_text.
MODIFY output FROM ls_output INDEX 1.
ENDIF.
ENDFORM. "TEST
Note: Check the text length.
