PLC Programming LED Control
Design a PLC ladder logic for the following application.
We are using three toggle Switches to control three LED’s
- If Toggle Switch 1 and Toggle Switch 2 are ON, then LED 1 and LED 2 will be ON.
- If Toggle Switch 2 and Toggle Switch 3 are ON, then LED 2 will be OFF, and LED 3 will be ON.
Digital Inputs
The required inputs are listed below.
Toggle Switch 1: I0.0
Toggle Switch 2: I0.1
Toggle Switch 2: I0.1
Here we call these toogle switches as simple “Switch” in our next discussions, But remember these are toggle-type switches.
Digital Inputs
The required outputs are listed below.
LED 1: Q0.0
LED 2: Q0.1
LED 3: Q0.2
Ladder Diagram for LED Control
PLC Program Description
- For this application, we used EcoStruxure Machine Expert Basic v1.2 software for programming.
- In the above program, we have used Normally Open Contacts for Switch 1 (I0.0), Switch 2(I0.1), and Switch 3 (I0.2). We have also used Normally Closed Contact for Switch 3 (I0.2).
- Switch 1 and Switch 2, present in Rung0 are connected in series for LED 1 and LED 2, thus implementing AND logic gate.
- With Switch 1 and Switch 2, Switch 3 is connected to LED 3 as Normally Closed Contact.
- For LED 3, Switch 2 and Switch 3 present in Rung1 are connected in series, thus implementing the AND logic gate.
- For LED 1 to be ON, Switch 1 and Switch 2 should be ON.
- When Switch 1 and Switch 2 are turned ON and Switch 3 is OFF, then LED 2 will be ON.
- When Switch 2 and Switch 3 are ON, LED 3 will be ON.
- Turning ON Switch 3 will turn OFF LED 2.
When Switch 1 and Switch 2 are ON
In Rung0, the signal through Switch 1 and Switch 2 when turned ON.
As a result, LED 1 and LED 3 will turn ON. Switch 3 is used as a Normally Closed Contact for Switch 3 when in a false state, it will allow the signal to turn ON LED 2.
When Switch 2 and Switch 3 are ON
The signal through Switch 2 and Switch 3 in Rung1, that turns ON LED 3.
In Rung0, switch 3 is taken as Normally Closed Contact, when in the true state, it will not allow signal to pass through it. As a result, LED 2 will turn OFF. Switch 3 is connected to LED 1 and therefore, it will remain ON.
PLC Tutorial Video
You can also watch the tutorial video below for this LED control PLC example program.
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