Allen-Bradley controllogix 1756-L61, Application Book

Page: 11 / 56

11 Publication LOGIX-AP007B-EN-P - January 2007
Chapter
2
CompactFlash File System Restrictions
Introduction This chapter describes the restrictions of the CompactFlash file system.
Restrictions of the File
System
The following are the restrictions of the CompactFlash file system.
Number of Open Files
The total number of open files at one time is one.
Maximum Data Per Message
The maximum amount of data that can be read or written to the
CompactFlash card at one time using the application is 450 bytes, this is
because we are using CIP Generic Messages. Attempts to read or write more
than this amount at one time is not permitted by the application code. If the
code is modified to access more than 450 bytes, the data will not be read or
written to the CompactFlash card. When you need to access more than 450
bytes of data, multiple calls to the file system must be performed and are
handled by the application code.
Removal and Insertion of CompactFlash Card
The application does not support the removal or insertion (RIUP) of the
CompactFlash card when a CompactFlash command is active.
Topic Page
Restrictions of the File System 11
Number of Open Files 11
Maximum Data Per Message 11
Memory Resources and Performance 12
Limited Life 12
Read or Write Portions of a File 12