PRACTICE PROBLEMS

(Note: Problem solutions are available at http://sites.google.com/site/automatedmanufacturingsystems/)

1. Write ladder logic that will give the following timing diagram for B after input A is pushed. After A is pushed any changes in the state of A will be ignored.

2. Design ladder logic for the timing diagram below. When an input A becomes active the sequence should start.

3. A wrapping process is to be controlled with a PLC. The general sequence of operations is described below. Develop the ladder logic using process sequence bits.

1. The folder is idle until a part arrives.

2. When a part arrives it triggers the part sensor and the part is held in place by actuating the hold actuator.

3. The first wrap is done by turning on output paper for 1 second.

4. The paper is then folded by turning on the crease output for 0.5 seconds.

5. An adhesive is applied by turning on output tape for 0.75 seconds.

6. The part is release by turning off output hold.

7. The process pauses until the part sensors goes off, and then the machine returns to idle.

4. Draw a timing diagram for the following ladder logic.

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