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Automating Manufacturing Systems - Process Control and ...

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plc timers - 9.32<br />

9.10 PRACTICE PROBLEM SOLUTIONS<br />

1. edge triggered means the event when a logic signal goes from false to true (positive edge) or<br />

from true to false (negative edge).<br />

2. no, but they are essential for retentive timers, <strong>and</strong> very important for counters.<br />

3. these are limited by the 16 bit number for a range of -32768 to +32767<br />

4. the un underflow bit. This may result in a fault in some PLCs.<br />

5.<br />

first pass<br />

stop<br />

U<br />

motor<br />

start<br />

L<br />

motor<br />

start<br />

motor<br />

stop<br />

motor<br />

6.<br />

input<br />

TON<br />

delays turning on<br />

TOF<br />

delays turning off

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