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Automating Manufacturing Systems - Process Control and ...

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plc timers - 9.21<br />

Solution:<br />

A<br />

TON<br />

Preset 15s<br />

delay<br />

delay.DN<br />

Light<br />

Figure 9.20<br />

A Simple Timer Example<br />

Problem: Develop the ladder logic that will turn on a light, after switch A has been<br />

closed 10 times. Push button B will reset the counters.<br />

Solution:<br />

A<br />

count.DN<br />

CTU<br />

Preset 10<br />

Accum. 0<br />

Light<br />

count<br />

B<br />

RES<br />

count<br />

Figure 9.21<br />

A Simple Counter Example<br />

9.7.2 More Timers And Counters<br />

Problem: Develop a program that will latch on an output B 20 seconds after input<br />

A has been turned on. After A is pushed, there will be a 10 second delay until A can have<br />

any effect again. After A has been pushed 3 times, B will be turned off.<br />

www.PA<strong>Control</strong>.com

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