Part -1:
Draw a state transition diagram for your garage door system.
- Include all possible states that you can begin or end with.
- Include all possible transitions that you can make from each state.
1. Design a PLC program using ladder logic that has two input and three outputs.
- Output 0 (Amber Light) represents the door traveling up.
- Output 1 (Green Light) represents the door traveling down.
- Output 2 (Red Light) represents the door being at any stopped state (Up, Down, or Stop).
- Input 0 should be a (simulated) normally closed optical trip sensor that will cause the door to go to the full up position.
- Input 1 is a single normally open push button.
- Input 1 should cause the door to go up if it is down.
- Input 1 should also cause the door to go down if it is up.
- While the door is traveling (up or down), pressing Input 1 should stop the door where it is. A second press of the button should cause the door to return to the up position.
- It takes 5 seconds for the door to travel from full down to full up, full up to full down, and also 5 seconds to travel from any stopped position to full up.
2. Utilize the RsLogix Emulator to develop and debug your program.
3. Demonstrate proper operation of the complete system on the hardware to the lab instructor.
Prepare a lab report as prescribed in the lab report template handed out on the first week.
1. Why is it so important to draw a state transition diagram before attempting to complete this lab?
2. What happens if the optical sensor is tripped while the door is traveling up?
3. What would be another type of instruction set, that you didn't use, that could be used to solve this problem?
4. What is different between your program and how a real garage door works?
5. How could you redesign your code in order to keep track of how far the door traveled before stopping so that you will finish the 5 second travel to the full up position?
Part -2:
Here is another project to test your skill as a PLC programmer. A traffic light has been installed at the intersection of two streets in front of ACME manufacturing. Your job is to write the logic to control and synchronize the traffic lights on both streets.
complete the following and turn it in at the beginning of your lab section.
1. Draw the timing diagram for the light sequence required in both the regular and override modes.
2. Draw the state transition diagram for the logic required to complete this lab
For this lab, use ladder logic or function block diagram programming to implement the program. You may wish to use a state machine, or an output sequencer (neither are required).
1. Utilize the following six digital outputs:
- Output 0 should cause the Main street Red light to illuminate.
- Output 1 should cause the Main street Amber light to illuminate.
- Output 2 should cause the Main street Green light to illuminate.
- Output 3 should cause the Cross street Red light to illuminate.
- Output 4 should cause the Cross street Amber light to illuminate.
- Output 5 should cause the Cross street Green light to illuminate.
2. Green lights should stay on for 10 seconds.
3. Amber lights should stay on for 3 seconds.
4. Red lights should stay on for the duration of the Green/Amber cycle of the opposing street plus a 2 second overlap with the opposing Red light.
5. Add logic to your program that causes the Red lights of the Cross street and the Amber lights of the Main street to ash alternately with an interval of 1 second in the event of an override (a bit set to high). The override bit need not be a hardware button (i.e. you may manually toggle a bit in the software to enter this mode).
6. Utilize a subroutine for the override state
7. Utilize the PLC emulator to develop and debug your program.
8. Assume that upon initial startup, the Cross street Red light is illuminated.
9. Demonstrate proper operation of the complete system to the lab instructor utilizing two of the stack lights attached to the PLC.
10. Create an Add-On Instruction that contains all of the logic for 1 light. Use this instruction 2 times to complete the exercise.
Post Lab
Prepare a lab report as prescribed in the lab report template handed out on the first week.
1. Draw the timing diagram for the light system.
2. Draw a state-transition diagram for the system. Show the state of each output for each state.
3. How might inductive sensors embedded in the road be added to sense the presence of a car to change the behavior of the system.
4. What state does your system resume to from the override state? Would this be a "safe" state to return to from override?
5. Could you make the program more efficient by not using a sub-routine or by adding more than one? Explain. of instruction set, that you didn't use, that could be used to solve this problem?