Planning Your System Programs
Chapter 6
6-8
Table 6.E
Data
T
able Memory Usage
File Type
File Type
Identifier
File
Number
Memory Used in Over
head for Each File
(16bit words)
Memory Used
(16bit 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
FloatingPoint F 8
1
2 2/float word
ASCII A 3999 2
1
/
2
per character
BCD D 3999 2 1/word
Undefined 9999 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:
PLC5/10, 5/12, 5/15 Is fixed at 32 words
PLC5/25 Varies from 3264 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.
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