# PLC Program to Implement 4:1 Multiplexer

This is a PLC Program to Implement 4:1 Multiplexer.

Problem Description

Implementing 4:1 multiplexer in PLC using Ladder Diagram programming language.

Problem Solution
• There are m-data inputs, one output and n select lines, with 2m = n.
• To select n inputs, we need m select lines such that 2m = n. Depending on the output. The selection of one of the n inputs is done by the select pins.
• It does not need K-map and simplification so one step is eliminated to create Ladder Logic Diagram.
• Realize the multiplexer using Logic Gates.
• Truth Table can be written as given below.
```Data	Select Inputs	Output
Inputs  S1	S0	Q
D0	0	0	D0
D1	0	1	D1
D2	1	0	D2
D3	1	1	D3```

Realizing 4:1 Mux using Logic Gates

PLC Program

Here is PLC program to Implement 4:1 Multiplexer, along with program explanation and run time test cases.

```List of Inputs and Outputs
S1=		I:1/0	(Select Line Input)
S0=		I:1/1	(Select Line Input)
D0=		I:1/2	(Data Line Input)
D1=		I:1/3	(Data Line Input)
D2=		I:1/4	(Data Line Input)
D3=		I:1/5	(Data Line Input)
Q=		O:2/0	(Output)```

Ladder Diagram to obtain Binary output

Program Description
• In all the rungs, S1 (I:1/0) and S0 (I:1/1) are used as a selector line input as shown in Logic Circuit.
• D0, D1, D2 and D3, I:1/2, I:1/3, I:1/4 and I:1/5 are Data Inputs respectively.
• When S1 (I:1/0) and S0 (I:1/1) are low, output will have whatever state D0 I:1/2 holds, either 1 or 0.
• When S1 (I:1/0) is low and S0 (I:1/1) is high, output will have whatever state D1 I:1/3 holds.
• Similarly remaining two different inputs are performed.
• In other words, according to bit pattern of S1 and S0, Data bits D0 to D3 are passed to output.
• Here, instead of bits D0 to D3, any functions such as moving, jumping or moving can be performed as well depending upon the application.
Runtime Test Cases
```Data    Select Inputs  Output
Inputs	S1     S0      Q
D0-0/1	0      0       D0-0/1
D1-0/1	0      1       D1-0/1
D2-0/1	1      0       D2-0/1
D3-0/1	1      1       D3-0/1```

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