FB_FileOpen

VAR_INPUT

VAR_INPUT
    sNetId      : T_AmsNetId;
    sPathName   : T_MaxString;
    nMode       : DWORD;
    ePath       : E_OpenPath := PATH_GENERIC;
    bExecute    : BOOL;
    tTimeout    : TIME;
END_VAR

sNetId    : is a string containing the AMS network identifier of the target device to which the ADS command is directed.

sPathName    : contains the path and file name of the file to be opened.

The path can only point to the local computer’s file system. This means that network paths cannot be used here!

nMode    : contains the mode in which the file is to be opened. The codes listed below are the various opening modes which are already pre-defined as constants in the library and which can accordingly be passed symbolically to the function block. The opening modes can be ORed.  The opening modes can be combined, similar to the opening modes of the fopen function in C or C++.

ePath    : this input can be used to select a TwinCAT system path on the target device for opening the file.

bExecute    : the function block is enabled by a rising edge at this input.

tTimeout    : states the timeout period that must not be exceeded when executing the ADS command.

VAR_OUTPUT

VAR_OUTPUT
    bBusy       : BOOL;
    bError      : BOOL;
    nErrId      : UDINT;
    hFile       : UINT;             (* file handle *)
END_VAR

bBusy:    This output remains TRUE until the block has executed a command, but at the longest for the duration supplied to the ‘tTimeout’ input. While bBusy = TRUE, no new command will be accepted at the inputs. Please note that it is not the execution of the service but its acceptance whose time is monitored.

bError:    This output is switched to TRUE if an error occurs during the execution of a command. The command-specific error code is contained in ‘nErrId’.

nErrId:    Contains the command-specific ADS error code of the most recently executed command. 

hFile:    Contains the file handle created for the file when opening has been successful.

Example of calling the block in FBD:

PROGRAM Test
VAR
    fbFileOpen      : FB_FileOpen;
    bFileOpen       : BOOL;
    bFileOpenBusy   : BOOL;
    bFileOpenError  : BOOL;
    nFileOpenErrId  : UDINT;
    hFile           : UINT;
END_VAR

This should create (or overwrite) the file ”TestFile2.txt" in the root directory of drive ”C:" in the text mode. 

For the opening mode a maximum of 3 parameters may be ORed: Mode = [ Parameter1 ] OR [ Parameter2 ] OR [ Paramerter3 ]

Parameter1 may have only one subordinate value:

• FOPEN_MODEREAD
• FOPEN_MODEWRITE
• FOPEN_MODEAPPEND

Parameter2 may have only one subordinate value:

• FOPEN_MODEPLUS

Parameter3 may have only one subordinate value:

• FOPEN_MODEBINARY
• FOPEN_MODETEXT

If no binary or text mode is specified, the file opens in a mode defined by an operating system variable. In most cases, the file will then open in text mode. However, it is not possible to make a clear statement. It is useful to always specify the text or binary mode. This system variable cannot be changed in the PLC!
This results in the following permissible combinations:

All other combinations are wrong. Examples of invalid opening modes:
FOPEN_MODEBINARY OR FOPEN_MODETEXT
FOPEN_MODEWRITE OR FOPEN_MODEAPPEND

Requirements