Basic AND gate operation explanation using electrical wiring diagram and PLC ladder diagram

Application:-Set wiring in the electrical panel so when operator has to operate two switches to operate one lamp. Make electrical control wiring using two switches and one lamp. Also draw truth table for application and write PLC program using ladder diagram language.

Diagram:-Electrical wiring diagram and truth table of AND operation

Explanation:-AND gate operations very important logic in various industrial application. For example purpose we have taken two switches S1 and S2 as shown in above figure. So if operator wants to ON lamp, he has to ON both the switches as per the AND operation. So S1 and S2 must be ON if we want to ON lamp.

In truth table all the conditions has been shown for explanation, it can be easily learned by simple conditional logic,

As per truth table,

If S1=ON AND S2=ON, then R=1

If S1=ON AND S2=OFF, then R=0

If S1=OFF AND S2=ON, then R=0

If S1=OFF AND S2=OFF, then R=0

So output will be ON only in first condition.

PLC program:-Write the ladder program for AND gate operation using ladder diagram language

Here for ladder logic we can use any PLC system. For PLC logic we need digital inputs and outputs.

For our application all switches are digital inputs and lamp is digital output. So define digital input address and output address as per below explanation,

Digital inputs:-

S1=I0.0

S2=I0.1

Digital Output:-

Lamp=Q0.0

Memory coil:-

M=Memory bit

PLC program Explanation:-

In network we have considered two digital inputs for two switches S1 and S2. So we have taken NO contact of S1 (I0.0) in series with S2 (I0.1) for AND operation. So when both are ON, memory bit (M0.0) will be ON.

In network 2 we have taken NO contact of memory bit (M0.0) to operate lamp (Q0.0).