I want to create a program to extract value from a file and create a sting (later I would want to use this string as an input value).

Also i found this solution to open the file and read the values. But I did not managed to make a string.

VAR_INPUT
   FileName : STRING := '/sys/bus/w1/devices/28-44260f1e64ff/w1_slave';
END_VAR
VAR_OUTPUT
   Done : BOOL := FALSE;
   ErrCode : SysFile.SYS_FILE_STATUS := SysFile.SYS_FILE_STATUS.FS_NO_FILE;
   Data : ARRAY[0..MAX_BUFFER] OF BYTE;
   BytesRead : __XWORD := 0;
END_VAR
VAR
   pResult : POINTER TO SysFile.RTS_IEC_RESULT;
   FileHandle : SysFile.RTS_IEC_HANDLE;
   pFileData : POINTER TO BYTE := ADR(Data);
END_VAR
//try to open file
FileHandle := SysFileOpen(szFile:= FileName, am:=AM_READ, pResult:=pResult);
//verify found a file
IF FileHandle = SysFile.RTS_INVALID_HANDLE THEN
   //no file found
   ErrCode := SysFile.SYS_FILE_STATUS.FS_NO_FILE;
   Done := TRUE;
ELSE
   //try to read file out
   BytesRead := SysFileRead(hFile:=FileHandle, pbyBuffer:=pFileData, ulSize:=MAX_BUFFER, pResult:=pResult);

   //check if actually read any bytes
   IF BytesRead > 0 THEN
      ErrCode := SysFile.SYS_FILE_STATUS.FS_OK;
   ELSE
      ErrCode := SysFile.SYS_FILE_STATUS.FS_NO_FILE;
   END_IF
   Done := TRUE;
END_IF
//close file!!!!
SysFileClose(hFile:=FileHandle);

Please help.

Hello,
I think it would be easier for you to use the CAAFile library instead of Sysfile.
The File.Open FB of the CAA_File library will directly return a string with the content of your file. You can find examples here.

You can use the "Read" functionality. When you call this (after you opened the file succesfully), the result is written in the buffer you have assigned when you call the Read function. Then it reads the amount of the size of the buffer, of if the file is smaller than the buffer, the whole file. From this buffer, you can use other functions to find the string you are looking for.

So in the example at the top, the variable "Data" will contain the contents you read from the file.

You can use the "Read" functionality. When you call this (after you opened the file succesfully), the result is written in the buffer you have assigned when you call the Read function. Then it reads the amount of the size of the buffer, of if the file is smaller than the buffer, the whole file. From this buffer, you can use other functions to find the string you are looking for.

So in the example at the top, the variable "Data" will contain the contents you read from the file.