Page 175 - Programmable Logic Controllers, Fifth Edition

8

Programming Counters

File type Counter number
C5:3
5 Counters
File number

Counter address
C5:3 Bit 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Word
C5:3.0 CUCDDNOV UN UA Internal use (not addressable)
0
Word
C5:3.1 Preset value
1
Word
C5:3.2 Accumulated value
2

Chapter Objectives

All PLCs include both up-counters and down- After completing this chapter, you will be able to:
counters. Counter instructions and their function • List and describe the functions of PLC counter
in ladder logic are explained in this chapter. Typi- instructions
cal examples of PLC counters include the follow- • Describe the operating principle of a transitional, or
ing: straight counting in a process, two counters one-shot, contact
used to give the sum of two counts, and two • Analyze and interpret typical PLC counter ladder logic
counters used to give the difference between programs
two counts. • Apply the PLC counter function and associated
circuitry to control systems
• Apply combinations of counters and timers to control
systems

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