1. Develop ladder logic for the flowchart below.

2. Use a flow chart to design a parking gate controller.

3. A welding station is controlled by a PLC. On the outside is a safety cage that must be closed while the cell is active. A belt moves the parts into the welding station and back out. An inductive proximity sensor detects when a part is in place for welding, and the belt is stopped. To weld, an actuator is turned on for 3 seconds. As normal the cell has start and stop push buttons.

a) Draw a flow chart

b) Implement the chart in ladder logic


4. Convert the following flowchart to ladder logic.

5. A machine is being designed to wrap boxes of chocolate. The boxes arrive at the machine on a conveyor belt. The list below shows the process steps in sequence.

1. The box arrives and is detected by an optical sensor (P), after this the conveyor is stopped (C) and the box is clamped in place (H).

2. A wrapping mechanism (W) is turned on for 2 seconds.

3. A sticker cylinder (S) is turned on for 1 second to put consumer labelling on the box.

4. The clamp (H) is turned off and the conveyor (C) is turned on.

5. After the box leaves the system returns to an idle state.

Develop ladder logic for the system using a flowchart. Don’t forget to include regular start and stop inputs.

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