Page 253 - Programmable Logic Controllers, Fifth Edition - Mobile version

11

Math Instructions

Input Ladder logic program Output
L1 L2
SW
SW MUL
MULTIPLY PL1
Source A N7:1
123
Source B N7:2
61
Destination N7:3
7503

PL1
EQU
EQUAL
Source A N7:3
7503
Source B 7503

Chapter Objectives

Most PLCs have arithmetic function capabilities. After completing this chapter, you will be able to:
Basic PLC math instructions include add, sub- • Analyze and interpret math instructions as they apply to a
tract, multiply, and divide to calculate the sum, PLC program
difference, product, and quotient of the content • Create PLC programs involving math instructions
of word registers. The PLC is capable of doing • Apply combinations of PLC arithmetic functions to
many arithmetic operations per scan period for processes
fast updating of data. This chapter covers the
basic mathematical instructions performed by
PLCs and their applications.

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