Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 194)

Block Transfer
Chapter 10
10Ć11
When the block transfer instructions are used, the first word and
consecutive words of the timer/counter accumulated area of the data table
must be reserved for block transfer data addresses.
Block transfer data addresses should be separated from the addresses
of timer and counter instructions by inserting a boundary. The last
consecutive word in the accumulated area following the words reserved
for block transfer data addresses should be loaded with zeroes. When the
processor sees this boundary word, it will not search further for block
transfer data. In addition, the processor is prevented from finding other
BCD values that could, by chance, be in the same configuration as the
rack, group and slot numbers found in block transfer data addresses.
The boundary word data bits can be set to zero manually using bit
manipulation [SEARCH] 53, or by Get/Put transfer. The Get/Put transfer
can be programmed by assigning the Get and Put instructions to the
address immediately following the last block transfer data address
(Figure 10.6). The value of the Get instruction is set to 000 when
programmed.
Figure 10.6
Defining the Data Address Area
000
( PUT )
000
032
| G |
032
Data Table
1 0 0 030
1 1 0 031
0 0 0 032
First word in accumulated area of
data table
Last consecutive data address
contains zeros to separate block
transfer addresses from timer,
counter, and storage addresses
10.7
Defining the Block Transfer
Data Address Area