Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 112)

Data Transfer File Instructions
Chapter 11
11-3
An internally indexed file instruction has a done bit and an enable bit. The
done bit is bit 15 and the enable bit is bit 17. These bits are automatically
entered from the counter address. The enable bit is set when the rung logic
goes from a false to true transition; the done bit is set when the file
instruction is completed.
There are three modes of operation based on the rate per scan. They are:
complete
distributed
complete
incremental
The following three sections describe each mode of operation.
Complete Mode
In the complete mode, the rate per scan is equal to the file length value and
the entire file is operated upon in one scan. For example, if there are 12
words in your file and your rate per scan value is 12 then all 12 words are
operated upon during one scan.
For each false-to-true transition of the rung condition, the instruction is
enabled, the accumulated value of the file counter is internally indexed
from the first to the last word of the file. As the accumulated value points
to each word, the operation defined by the file instruction is performed.
After the instruction has operated on the last word, the done bit (bit 15) is.
When the rung condition goes false, both the done and enable bits are reset
and the counter resets to position 001. If the rung was enabled for only
one scan, the done bit would come on during that scan and remain set for
one additional scan.
Distributed Complete Mode
In the distributed complete mode, the rate per scan is less than the file
length value and the entire file is operated over several program scans. For
example, if there are twelve words in your file and your rate per scan value
is three, then three words are operated upon during each scan. Therefore,
it takes four consecutive scans to execute the entire file
instruction operation.
Modes of Operation