Example written in ST

At a glance

In this example we use the following EFBs in order to perform some actions on a file:

CREATE_FILE,
OPEN_FILE,
SEEK_FILE
WR_DATA_TO_FILE
RD_FILE_TO_DATA
CLOSE_FILE

Declaration of variables

The table below shows the details of the variables to be declared for the parameters used:

Variable name	Type	Comment
close_req	EBOOL	Enable CLOSE_FILE function bit
create_req	EBOOL	Enable CREATE_FILE function bit
fileDesc	DINT	FileDesc is the number automatically assigned when a file is opened. This unique and temporary identification number will be assigned by the OPEN_FILE function.
NbBytesRd	UDINT	Specify the size effectively read of the variable.
read_req	EBOOL	Enable RD_FILE_TO_DATA function bit
variable	INT	variable read in the file
seek_req	EBOOL	Enable SEEK_FILE function bit
write_req	EBOOL	Enable WR_DATA_TO_FILE function bit
variable_tab	ARRAY[0..9] OF INT	Array for the different values of the variables written in the file
cmd_write	EBOOL	write file bit
GO_STORE	EBOOL	Bit used to start the creation of the file
cmd_seek	EBOOL	seek file bit
Error_WR	BOOL	Error during execution of WR_DATA_TO_FILE function bit
cmd_close	EBOOL	close file bit
GO_RESTORE	EBOOL	Bit used to start the re-opening of the file
open_req	EBOOL	Enable OPEN_FILE function bit
cmd_read	EBOOL	read file to data bit
Done_WR	BOOL	Writing in the file operation completed bit
Done_OPEN	BOOL	Opening the file operation completed bit
Status_WR	WORD	Error code (useful when Error_WR:=1)
Done_SEEK	BOOL	Seeking the file operation completed bit
Error_SEEK	BOOL	Error during execution of SEEK_FILE function bit
Status_SEEK	WORD	Error code (useful when Error_SEEK:=1)
Done_CREATE	BOOL	Creating the file operation completed bit
Error_CREATE	BOOL	Error during execution of CREATE_FILE function bit
Status_CREATE	WORD	Error code (useful when Error_CREATE:=1)
Done_CLOSE	BOOL	Closing the file operation completed bit
Error_CLOSE	BOOL	Error bit for CLOSE_FILE function
Status_CLOSE	WORD	Error code (useful when Error_CLOSE:=1)
Error_OPEN	BOOL	Error during execution of OPEN_FILE function bit
Status_OPEN	WORD	Error code (useful when Error_OPEN:=1)
Done_RD	BOOL	Reading the file operation completed bit
Error_RD	BOOL	Error during execution of RD_FILE_TO_DATA function bit
Status_RD	WORD	Error code (useful when Error_RD:=1)

Code

This code perform the following actions :

Create the file or seek it if it is already created,
Write data in the file,
Close the file,
Open the closed file,
Read the data written in the file,
Close the file.

(*********************************************************

Create a file 'TEST.bin' if doesn't exist and open it in

append mode(SEEK).

Write a data and close the file

*********************************************************)

(******* Begin CREATE part *******)

if RE(GO_STORE) then (* Set GO_STORE to start *)

  create_req := 1;

end_if;

CREATE (REQ := create_req,(* Rising edge on REQ input to start the CREATE *)

SLOT := 0,

FILENAME := 'TEST.bin',

MODEFLAG := 2,(* Read/Write mode *)

DONE => Done_CREATE,

ERROR => Error_CREATE,

STATUS => Status_CREATE,

FILEDESC => fileDesc);

create_req := 0;

if GO_STORE then

   if (Done_CREATE and not Error_CREATE) then

     GO_STORE := 0 ;

     seek_req := 1;

     cmd_seek := 1;

   end_if;

end_if;

(******* End CREATE part *******)

(******* Begin SEEK part *******)

SEEK (REQ := seek_req;(* Rising edge on REQ input to start the SEEK *)

FILEDESC := fileDesc

OFFSET := 0,

WHENCE := 2;

(* SEEK_END *)

DONE => Done_SEEK,

ERROR => Error_SEEK,

STATUS => Status_SEEK);

seek_req := 0;

if cmd_seek  then

   if (Done_SEEK and not Error_SEEK) then

     cmd_seek := 0;

     write_req := 1;

     cmd_write := 1;

   end_if;

 end_if;

(******* End SEEK part *******)

(******* Begin WRITE part *******)

variable_tab[0] := variable_tab[0] + 1;

WRITE (REQ := write_req,(* Rising edge on REQ input to start the WRITE *)

FILEDESC := fileDesc,

VARIABLE := variable_tab,

DONE => Done_WR,

ERROR => Error_WR,

STATUS => Status_WR);

write_req := 0;

if cmd_write then

  if (Done_WR and not Error_WR) then

    cmd_write := 0;

    close_req := 1;

    cmd_close := 1;

  end_if;

end_if;

(******* End WRITE part *******)

(******* Begin CLOSE part *******)

CLOSE (REQ := close_req,(* Rising edge on REQ input to start the CLOSE *)

FILEDESC := fileDesc,

DONE => Done_CLOSE,

ERROR => Error_CLOSE,

STATUS => Status_CLOSE);

close_req := 0;

if cmd_close then

  if (Done_CLOSE and not Error_CLOSE) then

    cmd_close := 0;

  end_if;

end_if;

(******* End CLOSE part *******)

(*********************************************************

Open the file 'TEST.bin',

read the first data and close the file

**********************************************************

(******* Begin OPEN part *******)

if RE(GO_RESTORE) then(* Set GO_RESTORE to start *)

  open_req := 1;

end_if;

OPEN (REQ := open_req,(* Rising edge on REQ input to start the OPEN *)

SLOT := 0,

FILENAME := 'TEST.bin',

MODEFLAG := 0,

DONE => Done_OPEN,

ERROR => Error_OPEN,

STATUS => Status_OPEN,

FILEDESC => fileDesc);

open_req := 0;

if GO_RESTORE then

  if (Done_OPEN and not Error_OPEN) then

    GO_RESTORE := 0 ;

    read_req := 1;

    cmd_read := 1;

  end_if;

end_if;

(******* End OPEN part *******)

(******* Begin READ part *******)

READ (REQ := read_req,(*  Rising edge on REQ input to start the READ *)

FILEDESC := fileDesc,

DONE => Done_RD,

ERROR => Error_RD,

STATUS => Status_RD,

VARIABLE => variable,

NBBYTESRD => NbBytesRd);

read_req := 0;

if cmd_read then

  if (Done_RD and not Error_RD) then

    cmd_read := 0;

    close_req := 1;(* Same CLOSE part than the CREATE/SEEK/WRITE/CLOSE *)

    cmd_close := 1;

  end_if;

end_if;

(******* End READ part *******)