Introduction to Industrial Automation

Figure 2.56  Pneumatic timer simplified internal view (a), and an OFF-Delay timer response (b).

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Hardware Components for Automation and Process Control 

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Several additional types of timers are available from the time-function point of view. For 

example, the delay-on with pulse activation timer, the flasher-type with an ON-OFF alternate 

change timer and the two-time-constants timer (T

1

 for ON and T

2

 for OFF) are some of them. 

More types of timers are described in Chapter 7, where PLCs contain multiple sets of timers each 

with multiple time functions. The use of timers in an automation system will be clear in Chapters 

3 and 4, where the synthesis of automation circuits including timers is presented.