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1772-6.8.3, 14 - bit shifts, 14ć1, Bit shifts – Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual User Manual

Page 253

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Chapter

14

14Ć1

Bit Shifts

The Bit Shift instructions are:

Bit Shift Left
Bit Shift Right
Examine Off Shift Bit
Examine On Shift Bit
Set Shift Bit
Reset Shift Bit

The Bit Shift Left and Bit Shift Right instructions are output instructions
used to construct and manipulate a synchronous bit shift register from
1 to 999 bits in length. Figure 14.1 shows a 128-bit shift register. Upon
false-true transition of rung decision the contents of the shift register
moves one bit to the right or left. Operation can only be in the complete
mode.

The Examine off Shift Bit and Examine On Shift Bit instructions are
condition instructions which can examine bits in a shift register such as
shown in Figure 14.1. The user specifies the bit number to be examined
and the starting address of the shift register.

Set Shift Bit and Reset Shift Bit are output instructions which set or reset
a specified bit in a bit shift register such as that shown in Figure 14.1. The
user specifies the bit number to be manipulated and the starting address of
the shift register.

NOTE: This section assumes the reader has read Chapter 12, file concepts
and data monitor mode, and is familiar with the concepts and terms
introduced in that section.

The Bit Shift Left output instruction constructs a synchronous bit shift
register from 1 to 999 bits in length. Figure 14.1A shows a 128-bit register
and ending at words 400

8

and 407

8.

14.0
General

14.1
Bit Shift Left