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Shift Registers 370

PLCs Training

Class Information

Tooling U classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and typically requires at least two hours of instruction time.

Class Name:	Shift Registers 370
Description:	This class explains the various register shifts than can be used in a PLC.
Prerequisites:	450200 450305
Difficulty:	Advanced
Number of Lessons:	12

Class Outline
Objectives What Is a Shift Register? PLC Bits Changing Bit Status Bit Change Applications Shift Register Functions Shift Left and Right Register Rotate Advanced Register Shifts Asynchronous Shift Register Shift Register Applications Summary

Class Objectives
Define shift registers. Describe PLC bits. Describe bit status change functions. Describe bit change applications. Describe shift register functions. Describe shift left and shift right. Describe register rotate. Describe advanced register shifts. Describe stacking functions. Describe shift register applications.

Class Vocabulary
bit clear		A PLC function that forces a specified bit to a 0.
bit follow		A PLC function that forces a specified bit to a 1 when ON, and a 0 when OFF.
bit set		A PLC function that forces a specified bit to a 1.
bit shift left		A shift register that shifts each bit one position forward. Shift left is the most common shift register.
bit shift right		A shift register that shifts each bit one position backward. Shift right is less commonly used than shift left.
enable bit		A status bit that activates PLC functions such as shift registers when the bit is ON.
FIFO		The most common stacking function that unloads data in the same order it was received. FIFO stands for first in, first out.
full register rotation		Reinserting the shifted out bit back a full 16 bits from where it was last located. Full register rotation is the most common type of register rotation.
LIFO		A less common stacking function that unloads data in the opposite order that it was received. LIFO stands for last in, first out.
multiple bit shift		An advanced shift register function that shifts bits multiple positions per shift. Sometimes called an N-shift.
multiple shift left		An advanced shift register function that shifts bits multiple positions to the left.
multiple shift right		An advanced shift register function that shifts bits multiple positions to the right.
N-shift		A multiple bit shift register. Called an N-shift because the variable N tells the processor how many positions to shift the bits.
partial register rotation		A function that can rotate the bit that was shifted out and insert it back somewhere into the middle of the word instead of at the beginning.
real-time value		The exact value of a bit of data. PLC register data is not considered real-time because values can change between PLC scans.
register rotate		A PLC function used with shift registers that takes the bit that was shifted out from one end of a word and inserts it at the opposite end of the word. This keeps the bit from being erased and maintains the bit pattern.
rotate left		A PLC function that takes the bit that was shifted out from the left end of a word and rotates it back to be inserted into the first bit position on the right.
rotate right		A PLC function that takes the bit that was shifted out from the right end of a word and rotates it back to be inserted into the last bit position on the left.
shift register		Shifting bits forward or backward within a word to vary how the outputs respond.
stacking function		A method of data manipulation that allows you to organize data relative to time and priority.