Page 150 - Programmable Logic Controllers, Fifth Edition - Mobile version
P. 150
7
Programming Timers
File type Timer number
T4:2
File number 15 14 13
4 Timers Word 0 EN TT DN
Word 1 Preset value
Word 2 Accumulated value
Chapter Objectives
After completing this chapter, you will be able to: The most commonly used PLC instruction, after
• Describe the operation of pneumatic on-delay and off- coils and contacts, is the timer. This chapter
delay timers deals with how timers time intervals and the way
• Describe PLC timer instruction and differentiate in which they can control outputs. We discuss
between a nonretentive and retentive timer the basic PLC on-delay timer function, as well as
• Convert fundamental timer relay schematic diagrams to other timing functions derived from it, and typical
PLC ladder logic programs industrial timing tasks.
• Analyze and interpret typical PLC timer ladder logic
programs
• Program the control of outputs using the timer
instruction control bits
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