Rockwell Automation 9323-S5500D A.I. SERIES MICROLOGIX 1000 AND PLC-500 SOFTW - Manual (Page 192)

MicroLogix 1000 and PLC-500 A.I. Series Software Reference
9-2
The Databases
Ladder logic documentation is stored in two databases:
•
Address (instruction) Descriptions
•
Page Titles and Rung Descriptions
Each of these has a separate editor.
Address Descriptions
An address description consists of the following.
•
An Address , which must be unique. Two database records cannot refer to a single
address, however, a particular memory location may be referred to by a bit address
and a word address. For example, N7:0 and N7:0/0 may each have a different
database record. Several types of instructions do not refer to an actual address;
these may be documented using pseudo-addresses (described on page 9-4 ).
•
A Symbol , which must be unique for each address. A symbol is up to 15
characters long, all uppercase.
Note If you are using the local mode for data files, you are allowed to use duplicate symbol
names, for example, if N10:0 is local to program file #2 and N11:0 is local to program
file #3, then you could use the same symbol for both addresses.
•
The Description , which can contain a maximum of five lines with 15 characters
each.
•
The Disable Xref flag. This is a field that can be used to prevent a frequently used
address from cluttering the ladder report cross reference.
•
Several additional fields are used to document I/O devices. These fields can only
be used in records that refer to physical I/O devices. When you edit internal
memory addresses, the I/O device fields are unavailable.
§ Device Code : a code identifying the type of device.
§ Abv and Blw : descriptive text to appear above and below the device in
reports.
§ Device Class : text describing the type of device.
§ Device Desc : text description of the particular device.