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Automating Manufacturing Systems - Process Control and ...

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plc sfc - 20.13<br />

Program 3 (for step #3)<br />

L<br />

power<br />

L<br />

light<br />

Program 10 (for transition #10)<br />

part detect<br />

EOT step 2<br />

Program 4 (for step #3)<br />

L<br />

advance<br />

L<br />

part hold<br />

Program 11 (for transition #10)<br />

bottom limit<br />

EOT step 2<br />

Figure 20.11<br />

Sample Ladder Logic for a Graphical SFC Program<br />

SFCs can also be implemented using ladder logic that is not based on latches, or<br />

built in SFC capabilities. The previous SFC example is implemented below. The first segment<br />

of ladder logic in Figure 20.12 is for the transitions. The logic for the steps is shown<br />

in Figure 20.13.<br />

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

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