a. A normally open field limit switch examined for an on state normally cycles f

Question

a. A normally open field limit switch examined for an on state normally cycles from on to off five times during one machine cycle. How could you tell by observing the LED status light that the limit switch is functioning properly?

b. How could you tell by observing the programming device monitor that the limit switch is functioning properly?

c. How could you tell by observing the LED status light whether the limit switch was stuck open?

d. How could you tell by observing the programming device monitor whether the limit switch was stuck open?

e. How could you tell by observing the LED status light if the limit switch was stuck closed?

f. How could you tell by observing the programming device monitor if the limit switch was stuck closed?

These questions are about PLCs!

Explanation / Answer

A- if limit switch is connected as a switch to plc input, then when you switch the limit switch on then the led indicator will glow. Hence we can simply check if the limit switch is functioning properly. Limit switch just completes the circuit hence you can also test it with a battery and a led using as a simple switch.

B- let us suppose that you have given the address I1 to the limit switch in the program. Go to online mode in plc program. Now when you press the limit switch you will see a blue light in I1 NO which means NO of I1 has become a NC, inside the program OVER the monitor. Which indicate that limit switch is working properly.

C- If the limit switch was stuck open the I1 input led status light will not glow anymore.

D- In the programming device monitor the NO of I1 will remain NO and NC of I1will remain NC. There will be no change when limit switch is stuck open. Even after pressing it will show the same if the problem is with the hardware part inside the switch.

E- Similarly when it is stuck closed the LED will be permanently glowing.

F- In this case the NO of I1 will become NC prmanently and NC of I1 will become NO permanently inside the program over monitor.

I HOPE MY ANSWERS HELPED YOU. PLEASE PROVIDE A GOOD RATING IF THIS WAS HELPFUL. IF ANY CONFUSION PLEASE WRITE IN THE COMMENT SECTION.

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