PLC Automatic Pedal Switch for Speed Control

We need to use pedal switch control logic at machine work shop for speed control of motor. Write the PLC program for this application using ladder diagram.

Pedal Switch for Speed Control

PLC Solution

Here we want to operate machine in two different speeds. For this control, we are using pedal switch so we can control the speed of motor.

For normal operation we need to operate machine in speed 1 condition. And for higher operation we need to operate machine in speed 2.

Here we have considered two different speeds of motor. so, by pressing pedal switch first time motor can be started at speed 1. When user will press pedal switch again motor will run at speed 2.

Motor can be stopped by pressing E stop button.

List of Inputs/Outputs

List of Inputs

• I1 : Pedal switch
• I2 : E stop button

List of Outputs

• Q1 : Speed 1
• Q2 : Speed 2

PLC Logic Automatic pedal switch for Speed Control

Ladder Logic Description

Network 1 :-

In this network, we have used pulse relay instruction for speed 1 output.

Network 2 :-

When pedal switch is triggered first time, it will operate on delay timer.

Network 3 :-

After some 2s delay motor will run at first speed.

Network 4 :-

In this network we have used another pulse relay instruction for the speed 2 output.

Network 5 :-

When pedal switch is triggered second time, it will operate on delay timer for the speed 2.

Network 6 :-

When timer is completed, motor will run at speed 2.

Note:- Above application may be different from actual application. This example is only for explanation purpose only. We can implement this logic in other PLC also. This is the simple automatic pedal switch for speed selection using PLC, we can use this concept in other examples also.

All parameters and graphical representations considered in this example are for explanation purpose only, parameters or representation may be different in actual applications. Also all interlocks are not considered in the application.

Author : Bhavesh

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