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.