Basic NOR gate operation explanation using electrical wiring diagram and PLC ladder diagram

Application:-In electrical panel there are two switches given for panel ON lamp. Both the switches are optional, the lamp can be OFF either by switch 1 or switch 2.Draw truth table, electrical wiring diagram and write PLC program for this application.

Components:-Programmable logic controller, Electrical panel, wires, 24vDC switches with NO contacts, 24VDC indication lamp, 24 VDC relay.

Diagram:-Electrical wiring diagram and truth table of NOR operation

Explanation:-

As per our application, we can use the above application for the NOR gate explanation. In the application, we are using two switches and one lamp for indication. If switch 1 or switch 2 pressed, an indication lamp should be OFF. So in the above electrical wiring diagram, we have used S1 and S2 in parallel connection so electrical supply can flow either from S1 or S2. We have used NC contact of relay for negative operation, hence the NOR gate.

In the truth table, we can easily understand the conditions of NOR gate,

As per truth table,

If S1=ON OR S2=ON, then R=0

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

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

If S1=OFF OR S2=OFF, then R=1

So the output will be ON only in the last condition.

PLC program:-

Write the ladder program for NOR 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 the lamp is a digital output. To 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:-

Memory bit-M0.0

PLC program Explanation:-

In-network 1 we have considered two digital inputs for two switches S1 and S2. So we have taken NO contact of S1 (I0.0) in parallel with S2 (I0.1) for NOR operation. So when S1 or S2 OFF, memory bit (M0.0) will be ON.

In-network 2 we have taken NC contact of memory bit (M0.0) to operate panel ON lamp (Q0.0).

Basic NAND gate operation explanation using the electrical wiring diagram and PLC ladder diagram

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

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

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

In the truth table, all the conditions have 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=0

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

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

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

So the output will be OFF only in the first condition.

PLC program:-Write the ladder program for NAND 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 the lamp is a digital output. To 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 1 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 NAND operation. So when both are OFF, memory bit (M0.0) will be OFF.

In-network 2 we have taken NC contact of memory bit (M0.0) to operate lamp (Q0.0).

Basic NOT gate operation explanation using electrical wiring diagram and PLC ladder diagram

Application:-Explain the NOT gate operation using electrical diagram and ladder diagram language. Draw electrical diagram for electrical panel in which lamp should be on when switch is off and lamp should be off when switch is off. Also write PLC program for this application using ladder diagram language.

Components:-Programmable logic controller, Electrical panel, wires, 24V DC switches with NO contacts, 24V DC indication lamp, 24 VDC relay,24V DC source.

Diagram:-Electrical wiring diagram and truth table of NOT gate operation

Explanation:-

In this application we need to use NOT gate logic. As shown in figure we can draw electrical diagram for NOT gate operation so that we have taken NO contact of switch S1 to operate lamps as per the NOT gate logic. Hence when switch is ON, relay is operated and lamp will be OFF due to NC contact of relay and when switch is OFF, lamp will be ON.

We can easily understand the NOT gate function with truth table,

If S1=ON, then R=0

If S1=OFF, then R=1

So NOT gate inverse the logic.

PLC program:-

Write the ladder program for NOT 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

Digital Output:-

Lamp=Q0.0

Memory coil:-

Memory bit-M0.0

PLC program Explanation:-

In network 1 we have used NO contact of switch S1 (I0.0) to operate memory bit (M0.0).So when S1 (I0.0) is ON memory coil (M0.0) is ON and switch S1 (I0.0) is OFF, memory coil (M0.0) will be OFF.

In network 2 we have used NOT gate function so when switch S1 (I0.0) is ON, it will inverse logic and makes lamp (Q0.0) OFF. And when S1 (I0.0) is OFF, lamp (Q0.0) is ON