Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 124)

Data Manipulation Instructions
Chapter 6
6Ć2
The Get Byte and Limit Test instructions compare 3-digit values in octal
format using eight bits (one byte) of a data table word (Figure 6.2). This
3-digit value is an octal number ranging from 000
8
to 377
8
. Note that two
3-digit values can be stored in a word: one in the upper byte (bits 10-17)
and one in the lower byte (bits 00–07).
A Data Manipulation instruction can address any word in the data table,
excluding processor work areas.
Figure 6.2
Octal Format
Upper Byte Lower Byte
2
1 0 0 1 1 0 0 1 1 1 1 0 1 1 1 1
Bits 00Ć07 Contain Octal Value of Lower Byte.
Bits 10Ć17 Contain Octal Value of Upper Byte.
3 1
8
3 5 7
8
2 1 2 0 2 1 2 0 2 2 2 1 2 0 2 2 2 1 2 0 2 1 2 0 2 2 2 1 2 0 2 2
There are three Data Transfer instructions. They are:
GET –|G|–
PUT –(PUT)–
GET BYTE –[B]–
Get instructions are programmed in the condition area of the ladder
diagram rung. They tell the processor to make a duplicate of all 16 bits
in the addressed memory word. When the rung containing the Get/Put
instructions goes true, the data is transferred to the word address of the Put
instruction (Figure 6.3).
6.1
Data Transfer Instructions
6.1.1
Get Instruction