Rockwell Automation 9323-S5500D A.I. SERIES MICROLOGIX 1000 AND PLC-500 SOFTW - Manual (Page 72)

MicroLogix 1000 and PLC-500 A.I. Series Software Reference
4-4
Naming and Describing a Data Table File
To describe a data table file, access the Data Table File screen (See page 4-2 for
instructions) and highlight the file you want to describe. Press [F4] Name . The system
asks you for a file name with a maximum of 10 characters. Type the filename, and
press [Enter] . The system asks for a file description with a maximum of 40 characters.
Type the description, and press [Enter] . The filename and description appear on the
Data Table File screen.
Changing the File Access Mode
The description database uses two file access modes for data table files:
•
Global allows access from any program file
•
Local allows access from only one program file.
Generally, you should use global access for your files, but there are instances where you
may want to limit access to a file. One such instance is when files contain information
that is only appropriate to one program file. In this case, you can limit access to
prevent accidental overwrites of the data. Another instance is for recipe programming,
where there are a multitude of similar activities for the same ladder program;
restricting access to critical data files to only those programs that use them prevents
confusing the recipe process.
Note The file access mode is not a function of the SLC 500 processor. It is still possible to
overwrite local data table values from other program files by using other software, by
using indirect addresses, or by indexed addressing beyond file boundaries.
To change the file access mode:
1. Access the Data Table File screen. (See page 4-2 for instructions.)
2. Highlight the file whose access mode you want to change, and press [F8] Filemod .
If the file was local, the system asks you if you want to switch its access mode to
global. Select [F1] Yes or [F5] No . If the file was global, the system asks you if
you want to switch its file access to local. Select [F1] Yes or [F5] No .
3. If you select local file access, the system asks you which program file number the
data table file should be local to. Type the file number, and press [Enter] .