Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 248)

Shift Register Instructions
Chapter 13
13Ć5
Figure 13.4
SHIFT FILE UP Example Rung
SHIFT FILE UP
COUNTER ADDR: 200
FILE LENGTH: 064
FILE: 400- 477
INPUT ADDR: 120
OUTPUT ADDR: 500
RATE PER SCAN: 064
200
(EN)
17
200
(DN)
15
This instruction can be used as a synchronous word shift register. When the
rung goes true, the data from a specified input word is shifted into the last
word file (Figure 13.1b), the data in the file is shifted down one word
(toward lower number addresses) and the data of the first word in the file is
shifted into the specified output word.
The instruction can operate in either complete or distributed complete
mode. In complete mode the input word data is shifted out in one scan. In
distributed complete mode, it will take a number of scans to shift in one
input word of data and to shift out one word of data to the output word.
The output word data should NOT be considered valid until the done bit
is set.
Instruction overview:
Output instruction
Key sequence: [SHIFT REG] 11
Counter manipulated by instruction
Can operate in distributed complete or complete modes
Requires 6 words of user program
WARNING: The counter address specified for the Shift File
Down instruction should be reserved for that instruction. Do not
manipulate the counter preset or accumulated values.
Inadvertent changes to these values could result in hazardous or
unpredictable machine operation or a run-time error. Damage to
equipment and/or personal injury could result.
13.2
Shift File Down
13.2.1
Programming Shift File
Down Instruction