Data Storage Elementary Functions

The following DataStorage_EF elementary functions are supported in Control Expert for all tasks in the M580 BMEH58•040 non-safety Hot Standby CPUs, and for process tasks in the M580 BMEH58•040S safety Hot Standby CPUs.

EF	Hot Standby CPU State
EF	Primary	Standby	Wait
`CREATE_FILE`	X	X	X
`DELETE_FILE`	X	X	X
`GET_FILE_INFO`*	X	X	X
`GET_FREESIZE`*	X	X	X
`OPEN_FILE`	X	X	X
`RD_FILE_TO_DATA`	X	X	X
`SET_FILE_ATTRIBUTES`	X	X	X
`WR_DATA_TO_FILE`	X	X	X
* Read-only function

NOTE: Changes made to an SD card in either the primary or standby CPU, using an elementary function, are not replicated in the SD card of the other CPU in the event of a switchover.

CREATE_FILE

The CREATE_FILE function creates a file called FILENAME, if it does not already exist. If a file by that name already exists, the CREATE_FILE command behaves the same as the OPEN_FILE command.

DELETE_FILE

The DELETE_FILE function deletes a file identified by its FILENAME. Close a file, using the CLOSE_FILE function before deleting it.

GET_FILE_INFO

The GET_FILE_INFO function retrieves information about a specified target file. Execute the OPEN_FILE function for the target file before executing the GET_FILE_INFO function, because the identity of the target file comes from the output parameter of the OPEN_FILE block.

GET_FREESIZE

The GET_FREESIZE function displays the amount of available space on the SD memory card.

OPEN_FILE

The OPEN_FILE function opens a specified file, provided the file already exists.

RD_FILE_TO_DATA

The RD_FILE_TO_DATA function allows data to be read from a file, at the current position of the file, and enables it to be copied to a variable.

SET_FILE_ATTRIBUTES

The SET_FILE_ATTRIBUTES function enables the setting of file attributes that set or clear the read-only flag for that file.

WR_DATA_TO_FILE

The WR_DATA_TO_FILE function writes the value of a specified variable to the selected file. The data written is added after the current position in the file.