The SCL file_open() function opens a file for subsequent reading.
file_open(fileOpenStatus, // file_open_status variable fileVar, // file variable fileName, // file name, String variable fileMode) // file mode (must be read_mode)
fileOpenStatus is a variable of type file_open_status. It receives the status result of the file open operation. It's values can be
mode_error // no longer used name_error // file not found open_ok // file successfully opened status_error // file already opened
fileName is a string containing the file name. It must contain the complete absolute path.
fileMode is a constant of type file_mode, however at this time the value must be "read_mode"