Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 128)

Sequencers
Chapter 12
12-2
Important: The data table is one word wide by many long. A sequencer
table appears in the data table as one continuous file. The length of the file
in the data table equals the product of the number of steps and the length as
shown in Figure 12.2. As an example, a 24 step x 4 word wide sequencer
table occupies 96 consecutive words in the data table.
Figure 12.2
Sequencer Table Format in the Data Table
Data Table
00 11 01 01 11 00 01 01
01 11 01 00 00 01 11 01
00 01 01 01 10 10 00 00
00 01 11 01
00 01 01 11
10 10 00 10
10 11 10 11
01 01 00 00
01 01 11 01
01 01 01 01
10 11 11 00
11 00 10 10
00 11 00 11
10 10 10 00
11 00 10 11
01 01 11 11
01 01 11 11
01 01 01 01
00 11 00 11
Data Table
Step 001
002
024
Step 001
002
024
Step 001
002
024
Step 001
002
024
Word #1
Word #2
Word #3
Word #4
The 4 words per
step (columns) of
the sequencer table
are located
sequentially in
the data table.
10152ĆI
Internally indexed file instructions perform the operation and then
increment to the next step. In contrast, internally indexed sequencer
instructions increment to the next step and then the operation is performed.
A special programming technique called a “mask” is used with the
sequencer instructions. A mask is a means of controlling what bits are
controlled/compared by the sequencer instruction. By masking bits, you
ensure that the sequencer instruction does not affect them. The masked
bits may then be used for other program purposes.
Mask