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20 - bit shift registers, 20ć1, Bit shift registers – Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual User Manual

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Chapter

20

20-1

Bit Shift Registers

This chapter describes bit shift instructions. The bit shift instructions are:

The Bit Shift Left or Right instructions move one bit to the left or right

upon the false-true transition of a rung. They are output instructions
that construct and manipulate a synchronous bit shift register from
1-999 bits in length. You can perform these operations only in the
complete mode.

The Examine Off or Examine On Bit Shift instructions are condition

instructions that examine bits in a shift register. You can specify the bit
number to be examined and the starting address of the shift register.

Bit Shift Set and Reset Bit Shift are output instructions that set or reset a

specified bit in a bit shift register. You can specify the bit number to be
manipulated and the starting address of the shift register.

The Bit Shift Left output instruction constructs a synchronous bit shift
register from 1-999 bits in length. Figure 20.1 shows a 128-bit register
starting and ending at words 400 and 407.

Chapter Objectives

Bit Shift Left