Hello,
I would like to use sysDir with sysdiropen and sysdirread but it does not work if someone can help me here the code (I made it from a codesys 2.3 and try to pass it on codesys 3.5 ):

PROGRAM POU
VAR
RUNIT :BOOL;
tempo :TON;
commande :STRING(255);
folder :POINTER TO BYTE ;
ENDREADFOLDER:UDINT;
NAMEELEMENTFIND: STRING(255);
INFOELEMENTFIND:DirInfo;
FOLDERRECEXISTING:BOOL;
END_VAR

IF visuelems.CURRENTVISU = 'Visu_Default' THEN
IF GVL_Keylist_RT.xKey_Return THEN
IF RUNIT=TRUE THEN
RUNIT:=FALSE;
ELSE
RUNIT:=TRUE;
END_IF
END_IF
IF GVL_Keylist_RT.xF2 THEN
folder:=SysDirOpen(szDir:= '/home/data' , szDirEntry:= '' , diMaxDirEntry:= 0, pDirInfo:= 0,pResult:= 0);
END_IF
IF GVL_Keylist_RT.xF3 THEN
sysdircreate('/home/data/REC');
END_IF
IF GVL_Keylist_RT.xF4 THEN
visuelems.CURRENTVISU := 'Visualisation';
END_IF
IF LANCER=TRUE THEN
REPEAT
ENDREADFOLDER := SysDirRead(hDir:= folder, szDirEntry:= FOLDERRECEXISTING,
diMaxDirEntry:=1024 , pDirInfo:=ADR(INFOELEMENTFIND));
IF INFOELEMENTFIND = '/REC' AND INFOELEMENTFIND.diDirectory = 2 (16#0 = fichier 16#2= Dossier ) THEN
( Dossier existant )
FOLDERRECEXISTING := TRUE;
END_IF
UNTIL
ENDREADFOLDER=0
END_REPEAT
IF FOLDERRECEXISTING = FALSE THEN
SysDirCreate('/data/REC');
END_IF
END_IF
END_IF

IF visuelems.CURRENTVISU = 'Visualization' THEN
IF GVL_Keylist_RT.xF4 THEN
visuelems.CURRENTVISU := 'Visu_Default';
END_IF
END_IF

There are some issues in how you are calling SysDirOpen and SysDirRead. I would suggest, for starters, looking at the File Utilities example on forge or to look more at the help files.
File Utilites example can be found here: https://forge.codesys.com/prj/codesys-example/file-utilities/home/Home/ or you can search the forge.