Definition of the Example and Declaration of Variables

Definition

The EFB WR_DATA_TO_FILE and RD_FILE_TO_DATA allow variables to be written into a file and data in a file to be read. These elementary functions make up part of the basis of file management and can therefore be used to build whatever type of application that requires these functions.

The example only uses the following four functions:

OPEN_FILE, to open an already created file,
WR_DATA_TO_FILE, to write data,
RD_FILE_TO_DATA, to read data,
CLOSE_FILE to close the file.

Declaration of Variables

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

Name of the variable.	Type	Comment
cmd_open	EBOOL	File opening bit.
cmd_write	EBOOL	Write data to file bit.
cmd_read	EBOOL	Read file data bit.
cmd_close	EBOOL	Close file bit.
FileName	STRING	File name. By default the value is ‘test’:
FileDesc	INT	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.

NOTE: The temporary identification number FileDesc enables, amongst other things, several people to open the same file at the same time to work on it. The number used for FileDesc is freed once the file is closed using the CLOSE_FILE function. FileDesc is managed automatically by the system.