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Automating Manufacturing Systems - Process Control and ...

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plc flowchart - 11.11<br />

F6<br />

MCR<br />

L<br />

outlet<br />

U<br />

inlet<br />

U<br />

L<br />

F6<br />

F2<br />

MCR<br />

Figure 11.9<br />

Ladder Logic for Operation F6<br />

11.3 SEQUENCE BITS<br />

In general there is a preference for methods that do not use MCR statements or<br />

latches. The flowchart used in the previous example can be implemented without these<br />

instructions using the following method. The first step to this process is shown in Figure<br />

11.10. As before each of the blocks in the flowchart are labelled, but now the connecting<br />

arrows (transitions) in the diagram must also be labelled. These transitions indicate when<br />

another function block will be activated.<br />

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