Page 65 - Programmable Logic Controllers, Fifth Edition

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Number Systems and Codes

0111 0101
0110 0100
1100
0010 Light source
1101
0011

0001 1111
1
1 1110
0000 0
1
1000 1010
1001 1011 Sensors

Photo Courtesy Baumer Electric.

Chapter Objectives

Using PLCs requires us to become familiar with After completing this chapter, you will be able to:
other number systems besides decimal. Some • Define the decimal, binary, octal, and hexadecimal
PLC models and individual PLC functions use numbering systems and be able to convert from one
other numbering systems. This chapter deals numbering or coding system to another
with some of these numbering systems, includ- • Explain the BCD, Gray, and ASCII code systems
ing binary, octal, hexadecimal, BCD, Gray, and • Define the terms bit, byte, word, least significant bit
ASCII codes. The basics of each system, as well (LSB), and most significant bit (MSB) as they apply to
as conversion from one system to another, are binary memory locations
explained. • Add, subtract, multiply, and divide binary numbers

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