(* 何如使用 ⇘ CAA_FILE.library示例 - 根路径或者路径功能块 *)

PROGRAM ROOT_PRG

VAR

                xRootInit:                 BOOL := FALSE;

                uiRootState:            UINT := 0;

                sStandarddir:          CAA.FILENAME:='C:/PLC_DIR';

                sDirName:               CAA.FILENAME;

                filsrt:                       FILE.SetRoot;

                filgrt:                       FILE.GetRoot;

END_VAR

 

IF NOT xRootInit THEN

                filsrt(xExecute:=FALSE);

                filgrt(xExecute:=FALSE);

                xRootInit:=TRUE;

                uiRootState:=0;

ELSE

                CASE uiRootState OF

                0: (* read root directory *)

                               filgrt( xExecute:=TRUE);

                               IF filgrt.xDone THEN

                                               sDirName:=filgrt.sFileName;

                                               uiRootState:=1;

                               END_IF

                               IF filgrt.xError THEN

                                               (* error handling*)

                                               ;

                               END_IF                      

                1:(* compare root directory *)

                               IF sDirName <> sStandarddir THEN

                                               uiRootState:=2;       (* set the new root *)

                               ELSE

                                               uiRootState:=3;       (* standard root directory already is set *)

                               END_IF

                2:(* set new root directory *)

                               filsrt.sFileName:=sStandarddir;

                               filsrt( xExecute:=TRUE);

                               IF filsrt.xDone THEN

                                               uiRootState:=3;

                               END_IF

                               IF filsrt.xError THEN

                                               (* error handling*)

                                               ;

                               END_IF

                3:             (* end of example*)

                                ;

                END_CASE

END_IF