Rockwell Automation 1785-LTx,D17856.2.1 Classic PLC-5 Programmable Controllers Users Manual - Manual (Page 79)

Planning Your System Programs
Chapter 6
6-8
Table 6.E
Data Table Memory Usage
File Type
File Type
Identifier
File
Number
Memory Used in OverĆ
head for Each File
(16Ćbit words)
Memory Used
(16Ćbit words) per
Word, Float Word,
Character, or Structure
Output Image O 0 2 1/word
Input Image I 1 2 1/word
Status S 2 2 1/word
Bit (binary) B 3 2 1/word
Timer T 4 1 2 3/structure
Counter C 5 1 2 3/structure
Control R 6 1 2 3/structure
Integer N 7 1 2 1/word
FloatingĆPoint F 8 1 2 2/float word
ASCII A 3Ć999 2 1 /
2
per character
BCD D 3Ć999 2 1/word
Undefined ĆĆ 9Ć999 2 0
1
This is the default file number. For this file type, you can assign any file number from 3 thru 999.
Data table files are contiguous in memory. Size in words for I/O files
0 and 1 are:
For this processor: Files O0 and I1 memory size:
PLCĆ5/10, Ć5/12, Ć5/15 Is fixed at 32 words
PLCĆ5/25 Varies from 32Ć64 words (32 is the default)
Status file 2 is fixed at 32 words for each processor. Files 3-999 vary in
size. These files contain only the number of words corresponding to the
highest address that you assign. Each B, N, A, and D file can be 1,000
words maximum. Each F file can be 1,000 float words (32-bit words)
maximum. Each T, C, R, and SC file can be 1,000 structures maximum.