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Automating Manufacturing Systems - Process Control and ...

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plc timers - 9.23<br />

Solution:<br />

Motor<br />

Stop<br />

C5:0<br />

RES<br />

Go<br />

Motor<br />

CTU<br />

Preset 2<br />

Accum. 1<br />

count<br />

count.DN<br />

Stop<br />

Motor<br />

Motor<br />

Light<br />

Consider:<br />

What will happen if stop is pushed <strong>and</strong> the motor is not running?<br />

Figure 9.23<br />

A Motor Starter Example<br />

9.7.4 Conveyor<br />

Problem: A conveyor is run by switching on or off a motor. We are positioning<br />

parts on the conveyor with an optical detector. When the optical sensor goes on, we want<br />

to wait 1.5 seconds, <strong>and</strong> then stop the conveyor. After a delay of 2 seconds the conveyor<br />

will start again. We need to use a start <strong>and</strong> stop button - a light should be on when the system<br />

is active.<br />

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

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