File Management

File Management functions provide the ability to do the following:

• Read machine recipes or other machine operational data into the .kas program from the SD card or a shared directory.
• Read cam tables into the program from the SD card or a shared directory.
• Store machine operational data in internal PxMM flash memory (retrievable through the web server), the SD card, or a shared directory.
  Please note that a shared directory connection is setup through the web server.

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• • If needed, functions to parse out information from a file using a string format can be found in String operations.
  • If the file is in .CSV format, the following functions can be used: LogFileCSV, ApplyRecipeColumn
  • You can create, store, and retrieve recipes and other data using:
    • the AKI Terminals. For more information see the KVB manual.
    • through an external bus connection to the PxMM with a supported fieldbus, such as UDP or HTTP.

The following function blocks enable sequential read / write operations in disk files:

Fucnction Block	Use
FileClose	Close an open file
FileCopy	Copy a file
FileDelete	Remove a file
FileEOF	Test if the end of the file is reached in a file that is open for reading
FileExists	Test if a file exists
FileOpenA	Create or open a file in append mode
FileOpenR	Open a file for reading
FileOpenW	Create or reset a file and open it for writing
FileReadBinData	Read binary data from a file
FileReadLine	Read a string value from a text file
FileRename	Rename a file
FileSeek	Set the current position of a file
FileSize	Get the size of a file
FileWriteBinData	Write binary data to a file
FileWriteLine	Write a string value to a text file

The following functions handle mounting of SD cards.

Name	Use
SD_ISREADY	Check that the SD card is ready for read/write
SD_MOUNT	Mount an SD card
SD_UNMOUNT	Unmount an SD card

Each file is identified in the application by a unique handle manipulated as a DINT value. The file handles are allocated by the target system. Handles are returned by the Open function blocks and used by all other function blocks for identifying the file.

Related function blocks:

LogFileCSV  log values of variables to a CSV file

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• • Files are opened and closed directly by the Operating System of the target. Opening some files can be dangerous for system safety and integrity. The number of open files (from FileOpenA, FileOpenR, and FileOpenW) is limited by the resources available on the target system.
  • Ensure that each file successfully opened using FileOpenA, FileOpenR, and FileOpenW has a corresponding FileClose to close the file. Closing the file will release the file ID, making it available for operations on other files.
  • The deprecated functions will stall the PLC "Programmable Logic Controller" A Programmable Logic Controller, PLC, or Programmable Controller is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Used to synchronize the flow of inputs from (physical) sensors and events with the flow of outputs to actuators and events, causing the controller to miss PLC cycles.
  • The IDs used by the file function blocks are not compatible with the deprecated file functions.
  • The IDs used by the deprecated file functions are not compatible with the file function blocks.

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• • Opening a file with FileOpenA, FileOpenR, and FileOpenW can be unsuccessful (invalid path or file name, too many open files...) Your application must check the file ID for a NULL value. If the file ID is NULL (zero), then file read or write operations will fail.
    
  • File management may be unavailable on some targets.
    
  • Memory on the SD card is available in addition to the existing flash memory.
    
  • Valid paths for storing files depend on the target implementation.
    
  • Error messages are logged in the Controller log section of KAS Runtime In computer science, runtime (or run-time) describes the operation of a computer program, the duration of its execution, from beginning to termination (compare compile time). Within KAS, runtime also refers to the virtual machine that manage the program written in a computer language while it is running where there is a failure in any related function block.
    
  • Using the KAS Simulator, all pathnames are ignored, and files are stored in a reserved directory. Only the file name passed to the Open functions is taken into account.
    
  • AKD PDMM / PCMM files are big endian.

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• Be sure to review File Path Conventions to understand hardware-based functional differences.