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Automating Manufacturing Systems - Process Control and ...

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plc sfc - 20.11<br />

step 6<br />

U<br />

step 6<br />

L<br />

transition 6<br />

Figure 20.9<br />

SFC Implemented in Ladder Logic<br />

Many PLCs also allow SFCs to entered be as graphic diagrams. Small segments of<br />

ladder logic must then be entered for each transition <strong>and</strong> action. Each segment of ladder<br />

logic is kept in a separate program. If we consider the previous example the SFC diagram<br />

would be numbered as shown in Figure 20.10. The numbers are sequential <strong>and</strong> are for<br />

both transitions <strong>and</strong> steps.<br />

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

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