Question

Please design a PLC program to perform the following task:

1. An LED will be on when it’s activated by an NO push button for an accumulated 6 seconds. In other words, the push button can be on and off, but when it’s accumulated for six seconds, the LED will be on.
2. After six seconds, the LED will be on for four seconds and is then reset itself for another cycle.

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Cascading timer

1. Assume the maximum allowable time preset is 5 seconds. Please design a cascading timer will activate an LED in 8 seconds.

Answer 1

Solution is attached below.

Details:

I:1/0 NO push button(start button)

T4:0 timer 1(TON)

t4:1 timer 2(TON)

O:2/0 LED

Working:

Rung 000: When NO push button I:1/0 is pressed, it initiates(starts) the TON timer T4:0. The Enable bit (T4:0/EN) becomes active and latches the start circuit, so when the Push button is released the program doesn't stops.

Rung 001: After 6 sec, the Timer 1(T4:0) Done Bit (T4:0/DN) becomes high and starts the second TON timer T4:1 .

Rung 002: When second timer T4:1 starts, it enable bit (T4:1/EN) becomes high and starts the LED( O:2/0) for 4 sec.

Rung 003: After 4 sec, the Done bit(T4:1/DN) of timer 2(T4:1) becomes which reset both the timer 1&2.

Now for another cycle, the NO push button I:1/0 must be pressed again.

NOTE:

please let me know if you need a program for the last two statement also.

Do share your feedback and let me know if you need further explanations