Question

Write a SFC program to operate a light according to the following sequence:

• A momentary pushbutton is pressed to start the sequence.

• The light is switched on and remains on for 2 s.

• The light is then switched off and remains off for 2 s.

• A counter is incremented by 1 after this sequence.

• The sequence then repeats for a total of 4 counts. • After the fourth count, the sequence will stop and the counter will be reset to zero.

Answer 1

To operate a light according to the given sequence, you can write a Sequential Function Chart (SFC) program.

Step-by-step explanation:

To operate a light according to the given sequence, you can write a Sequential Function Chart (SFC) program. Below is an example of how to implement the desired sequence:

1. Declare a boolean variable 'startButton' to keep track of the momentary pushbutton state.
2. Initialize a counter variable 'count' to zero.
3. Start the SFC program with an initialization step to reset all variables.
4. Use a 'Step' element with a condition 'startButton' to wait for the momentary pushbutton to be pressed.
5. After the pushbutton is pressed, toggle the state of the light output and wait for 2 seconds using a 'Timer' element.
6. Toggle the state of the light output again and wait for another 2 seconds.
7. Increment the 'count' variable by 1.
8. Use a 'Transition' element to check if 'count' is equal to 4. If true, transition to the End step. If false, transition back to the step where the pushbutton is waited for.
9. End the SFC program and reset the 'count' variable to zero.

This SFC program will repeat the sequence for a total of 4 counts, and then stop and reset the counter.