Learn how to create PLC program based on logic circuit to enhance your automation skills with our tutorials and videos.
Important: This PLC logic is solely for educational purposes and helps students and technicians grasp PLC fundamental concepts.
Create PLC Program
Problem Statement:
Design a PLC ladder logic for the following Logic Circuit.
We are using toggle Inputs to control the output.
PLC Tutorial Video
Watch the video to understand the PLC concepts for a beginner level.
Inputs
The list of DI signals is listed below.
A: I0.0
B: I0.1
C: I0.2
D: I0.3
Outputs
The list of DO signals is listed below.
Y: Q0.0
Ladder Diagram
PLC Program Explanation
- Here we used Schneider Electric PLC programming software. You can try any other PLC software too.
- In this PLC program, Normally Open Contacts are used for input A, input B, input C, and input D.
- Input A and Input B are connected in parallel, thus implementing OR Logic Gate.
- There is again the implementation of OR Logic Gate as Input C and Input D are connected in parallel.
- AND Logic Gate is also implemented as A + B is connected in series with C + D.
- For the output Y (Q0.0) to be ON, Input A or Input B and Input C or Input D should be ON.
PLC Test Results
The PLC program test results with different inputs are shown below.
When Input A and Input C are ON
The signal will flow through Input A and Input C when these Inputs are turned ON as Normally Open Contact is used. As a result, the output Y (Q0.0) will turn ON.
When Input A and Input D are ON
When Input A and Input D are ON, Y(Q0.0) will turn ON as Normally Open Contacts used for these Inputs are in True state.
Instead of using input C, we can also use input D to turn ON the output Y (Q0.0).
When Input B and Input C are ON
The output Y (Q0.0) will turn ON when Normally Open Contacts used for Input B and Input C are in True state and will pass signal to flow.
Here, instead of using input B, we can also use input B to turn ON the output Y (Q0.0).
When Input B and Input D are ON
Turning On Input B and Input D will turn ON Y(Q0.0), as the signal will flow through Input B and Input D and will turn ON (YQ0.0).
Therefore, we can also use input B and input D to turn ON the output Y (Q0.0).
When three inputs are ON
When three inputs i.e., either input A, input B, and input C or input A, input B, and input D or input B, input C, and input D are turned ON, then the output Y (Q0.0) will turn ON.
For output Y (Q0.0) to be ON, two inputs i.e., input A and input C or input D or input B and input C or input B and input D should be ON.
Turning ON the third input will not turn OFF the output Y (Q0.0). Therefore, if any three inputs are turned ON, the output will be ON.
When all Inputs are ON
When Input A, Input B Input C, and Input D, all are turned ON, the output Y (Q0.0) will be ON. Turning ON all the inputs will not turn OFF the output Y (Q0.0).
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