11.13 ASSIGNMENT PROBLEMS

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1. Draw a schematic symbol for a solenoid controlled pneumatic valve and explain how the valve operates.

3. A PLC based system has 3 proximity sensors, a start button, and an E-stop as inputs. The system controls a pneumatic system with a solenoid controlled valve. It also controls a robot with a TTL output. Develop a complete wiring diagram including all safety elelemnts.

4. A system contains a pneumatic cylinder with two inductive proximity sensors that will detect when the cylinder is fully advanced or retracted. The cylinder is controlled by a solenoid controlled valve. Draw electrical and pneumatic schematics for a system.

5. Draw an electrical ladder wiring diagram for a PLC controlled system that contains 2 PNP sensors, a NO pushbutton, a NC limit switch, a contactor controlled AC motor and an indicator light. Include all safety circuitry.

2. We are to connect a PLC to detect boxes moving down an assembly line and divert larger boxes. The line is 12 inches wide and slanted so the boxes fall to one side as they travel by. One sensor will be mounted on the lower side of the conveyor to detect when a box is present. A second sensor will be mounted on the upper side of the conveyor to determine when a larger box is present. If the box is present, an output to a pneumatic solenoid will be actuated to divert the box. Your job is to select a specific PLC, sensors, and solenoid valve. Details (the absolute minimum being model numbers) are expected with a ladder wiring diagram. (Note: take advantage of manufacturers web sites.)