Explain ON delay timer using electrical drawing and PLC program.

Application:-ON delay timer explanation. Explain On delay timer using example and draw electrical diagram and write PLC program for example.

Components:-Programmable logic controller, Electrical panel, wires, 24VDC switch with NO contacts, 24VDC solenoid valve, and 24 VDC timer.

Explanation:-

Consider one example for ON delay timer explanation. For example there is a valve in our application and we need to operate it after 20sec when switch S1 is pressed. So as show in above circuit supply will pass from No contact of the switch and will go to timer supply. When switch is pressed timer will start first and timer is completed, it will allow supply to pass from its NO contact. Adjust timer time from the dial as per requirement.

PLC program:-

Write the ladder program for above application using ladder diagram language. Here for ladder logic we can use any supported PLC system like S7-1200, S7-300, S7-1500 or any other PLC which can support this instruction. For PLC logic we need digital inputs and outputs.

For our application start switch S1 is digital input and valve is the digital output. So define digital input address and output address as per below explanation,

Digital inputs:-

Start switch S1=I0.0

Digital Output:-

Valve=Q0.0

PLC program Explanation:-

In network 1 we have taken NO contact of Start switch S1 (I0.0) so when switch is pressed, timer will start. The set time is 20sec so timer will generate command and it will operate the valve (Q0.0).

Here PT is preset time at which we can set time and ET is elapsed time at which we can monitor time. Do not mix up the pulse timer and ON delay timer. In pulse timer ,timer needs pulse of the digital input for operation and in ON delay timer, timer needs digital input for operation.

Explain basic pulse timer of PLC using example

Application:-Explain pulse timer using example. Operate solenoid after 10 second in the control panel when start button pressed. Solenoid should be ON after 10 seconds. Draw electrical circuit and write PLC program using ladder diagram language.

Components:-Programmable logic controller, Electrical panel, wires, 24vDC switches with NO contacts, 24VDC solenoid valve, and 24 VDC timer.

Diagram:-Electrical wiring diagram of solenoid operation with pulse timer.

Explanation:-

Generate pulse timer can be used for many application. It can be used to set output for some duration.

The instruction is started when the result at IN changes from 0 to 1.Positive edge of the input can be used in this timer. Once positive edge of the signal is detected timer will start and it will remain ON till its time completed.

Here in above application we will use pulse timer. We want to ON solenoid after 10 seconds and we have one push button. So when operator press start button, after 10 second solenoid should be ON. In above application when start button is pressed timer will start and after 10 second timer’s NO contact will start the solenoid.

PLC program:-

Write the ladder program for above application using ladder diagram language. Here for ladder logic we can use any supported PLC system like S7-1200, S7-300, S7-1500 or any other PLC which can support this instruction. For PLC logic we need digital inputs and outputs.

For our application start pushbutton is digital input and valve is the digital output. So define digital input address and output address as per below explanation,

Digital inputs:-

Start PB=I0.0

Digital Output:-

Valve=Q0.0

PLC program Explanation:-

In network 1 we have taken NO contact of Start push button (I0.0) so when push button pressed, timer will get positive edge of start pushbutton and start to count time. Once 10s is completed, valve (Q0.0) will be ON.

Here user can set required time at PT and can watch time at ET (Elapsed time).

Combinational logic operation using AND gate and OR gate

Application:-Draw electrical diagram and write PLC program for combinational logic for 3 switches. Use AND gate and OR gate for three switches combinational logic. Operate lamp in the following condition,

If S1 or S2 is ON and S3 is ON, the lamp will be ON.

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


Diagram:-Electrical wiring diagram for combinational logic.

Explanation:-

Here we have 3 switches S1, S2, and S3. So the condition is either S1 or S2 should be ON or S3 should be ON. So S1 and S2 should be put in OR gate and this combination should be put in series with S3.

Hence the lamp will be ON if S1 or S 2 is ON and S3 is ON.

PLC program:-

Write the ladder program for combinational logic 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

S3=I0.2

Digital Output:-

Lamp=Q0.0

Memory coil:-

Memory bit-M0.0

PLC program Explanation:-

In-network 1 we have considered three digital inputs for three switches S1, S2, and S3. So we have taken NO contact of S1 (I0.0) and S2 (I0.1) in OR gate and. So when S1 or S2 OFF, memory bit (M0.0) will be ON.