Allen-Bradley PLC-2/30

Data Manipulation Instructions
Chapter 6
62
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
1001100111101111
Bits 0007 Contain Octal V alue of Lower Byte.
Bits 1017 Contain Octal V alue of Upper Byte.
31
8
357
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
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