The beauty of SCL is that offers you, like the saying says "1000 ways to skin a cat"
here is a simple example,oboiusly the use of SFC20 is the proper way to do it. but when I did not know how to parametrize it in SCL I always used as follows

attached is the SCL just ready to import into your project sources.
give it a test, I Just wrote it but,in this computer I do not have a SIMULATOR installed, so did not thest functionality,but the compilation did not produce any error, so it will work.

FUNCTION FC2010 : VOID

VAR_INPUT
TRIGGER: BOOL;
SOURCE_DB: WORD;
SOURCE_INITIAL_BYTE: INT;
DESTINATION_DB: WORD;
DESTINATION_INITIAL_BYTE: INT;
NUMBER_OF_BYTES: INT;
END_VAR

VAR_TEMP
I: INT;
END_VAR
BEGIN
IF TRIGGER THEN
FOR I:=0 TO NUMBER_OF_BYTES DO
WORD_TO_BLOCK_DB(DESTINATION_DB).DB[DESTINATION_INITIAL_BYTE+I]:=WORD_TO_BLOCK_DB(SOURCE_DB).DB[SOURCE_INITIAL_BYTE+I];
END_FOR;
END_IF;
END_FUNCTION