Question

Imagine you are working in a company that designs and manufactures industrial washing machines.You are asked to make a 1-program machine with 2 buttons. Design requirements are as follows:

✓ If the user presses only X then Program1 will run. (PS: Please note that the buttons are toggle button)
✓ The wash cycle for program should be 25 minutes.
✓ After completing a wash, wait 10 minutes before starting a new wash. Even if the user logs in, the new wash should not be started.
✓ If Program 1 is selected, the motor should periodically perform 45 seconds turn right, 30 seconds wait and 45 seconds turn left, 30 seconds wait.
✓ If the Emergency stop button is pressed, the system should stop and if it is released, it should continue to run from where it left off.

a)Describe the events.
b)Draw automata model.
c)Achieve the functions of the states.
d)Write the PLC program using Ladder diagrams.

Answer 1

Events

button X presses

1.Motor running

Forward direction : 45 sec

Stop time: 30 sec

Reverse direction: 45sec

Stop time : 30 sec

This occurs for 10 cycles (wash time 25×60=1500 sec; 45+30+45+30=150sec per cycle)

Stop time 600sec ( 10 min)

Motor stops running

2. Interrupt ( toggle) button Y pressed

Motor stops running

Button Y released

Return to 1

Motor starts running where left

Automata model: