Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 126)

Data Manipulation Instructions
Chapter 6
6Ć4
Figure 6.4
Changing a Counter Preset
|ą|
11
( PUT )
238
111 140
|ą|
12
( CTU )
111 040
| G |
238
130
PR 238
AC 047 NOTE: The Preset of the Counter at
Address 040 is at Address 140.
The lower 12 bits of transferred data are displayed in BCD beneath the Put
instruction. Bits 14-17 are not displayed but are transferred. While the rung
is true, any change in the data of the Get instruction also changes the data
of the Put instruction. However, the Put instruction is retentive, which
means that, while the rung is false, any change in the data of the Get
instruction does not change the data of the Put instruction.
The Data Comparison instructions are:
LESS THAN –|<|–
EQUAL TO –|=|–
GET BYTE –|B|–
LIMIT TEST –|L|–
Data comparison operations differ from data transfer operations in that
data table values are not transferred. Instead, the values at different word
locations are compared.
Data comparison instructions operate with either BCD values or octal
values. With the Les and Equ instructions, only 12 bits of a word (the data)
are compared. Bits 14-17 are not compared. With the Get Byte and Limit
Test instructions, 8 bits in a word are compared.
The Les (less than) and Equ (equal to) instructions are used with the Get
instruction to perform data comparisons. They compare BCD values and
are programmed in the condition area of the ladder diagram rung.
6.2
Data Comparison
Instructions
6.2.1
Les and Equ Instructions