# PLC Program to Implement 8:1 Multiplexer

This is a PLC Program to Implement 8:1 Multiplexer.

Problem Description

Implementing 8:1 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	S2	S1	S0      Q
D0	0	0	0	D0
D1	0	0	1	D1
D2	0	1	0	D2
D3	0	1	1	D3
D4	1	0	0	D4
D5	1	0	1	D5
D6	1	1	0	D6
D7	1	1	1	D7```

Realizing 8:1 Mux using Logic Gates

PLC Program

Here is PLC program to Implement 8:1 Multiplexer, along with program explanation and run time test cases.

```List of Inputs and Outputs
S2=		I:1/0	(Select Line Input)
S1=		I:1/1	(Select Line Input)
S0=		I:1/2	(Select Line Input)
D0=		I:1/3	(Data Line Input)
D1=		I:1/4	(Data Line Input)
D2=		I:1/5	(Data Line Input)
D3=		I:1/6	(Data Line Input)
D4=		I:1/7	(Data Line Input)
D5=		I:1/8	(Data Line Input)
D6=		I:1/9	(Data Line Input)
D7=		I:1/10	(Data Line Input)
Q=		O:2/0	(Output)```

Program Description
• In all the rungs, S2 (I:1/0), S1 (I:1/1) and S0 (I:1/2) are used as a selector line input as shown in Logic Circuit.
• D0 to D7, I:1/3 to I:1/10 are Data Inputs respectively.
• When S2 (I:1/0), S1 (I:1/1) and S0 (I:1/2) are low, output will have whatever state D0 I:1/3 holds, either 1 or 0.
• When S2 (I:1/0) and S1 (I:1/1) are low and S0 (I:1/1) is high, output will have whatever state D1 I:1/4 holds.
• Similarly remaining six different inputs are performed.
• In other words, according to bit pattern of S2, S1 and S0, Data bits from D0 to D7 are passed to output.
• Here, instead of bits D0 to D7, 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       S2(I:1/0) S1(I:1/1) S0(I:1/2)  Q(O:2/0)
D0 (I:1/3)	0	  0	    0	   D0 0 or 1
D1 (I:1/4)	0	  0	    1      D1 0 or 1
D2 (I:1/5)	0	  1	    0	   D2 0 or 1
D3 (I:1/6)	0	  1	    1	   D3 0 or 1
D4 (I:1/7)	1	  0	    0	   D4 0 or 1
D5 (I:1/8)	1	  0	    1	   D5 0 or 1
D6 (I:1/9)	1	  1	    0	   D6 0 or 1
D7 (I:1/10)	1	  1	    1	   D7 0 or 1```

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