Rockwell Automation 1785 PLC-5 User Manual download pdf (Page 56)

Publication 1785-UM012D-EN-P - July 2005

4-12 Addressing I/O and Controller Memory

TIP

You might also want to leave room for future expansion

when grouping data. Do this by leaving gaps between:

• data blocks within a file

• groups of sequentially numbered files

• modules in an I/O chassis

IMPORTANT

If you plan to edit your program online in Run mode, you

must allocate unused data table files/elements and program

files because you cannot create user memory while in run

mode. Each unused file, however, uses 6 words of overhead

memory for each data/program file you skip. Use care

when leaving gaps.

TIP

Follow these guidelines when organizing data files:

• Group large amounts of related data into files.

• Address the data files from 3-999 as needed.

(See on page page 13).

• Address the words needed in each data file

consecutively from 0-999 (0-1999 for some data types

in series E, revision D controllers and later).

• Address the words of I/O image data according to how

you configured your I/O:

– 0-37 (octal) for PLC-5/11, -5/20, -5/20E

– 0-77 (octal) for PLC-5/30

– 0-177 (octal) for PLC-5/40, -5/40L, -5/40E

– 0-277 (octal) for PLC-5/60, -5/60L, -5/80, -5/80E

• When addressing I/O image bits, address them 00-07

or 10-17 (octal).

• When organizing bit data, address the bits in each word

0-15 (decimal) for binary or integer files.

Each data table file allocates 6 words of memory when you

create the file. This is in addition to any data stored in the

file.

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Rockwell Automation 1785 PLC-5 User Manual Page 56