Introduction to Industrial Automation

Figure 10.1  Cyclic operation of traffic lights.

Blac

k

Whit

e

Top view

Side view

Metallic

plate

PC

1

PC

2

PC

1

PC

1

C

1

C

2

C

3

C

4

C

5

PC

2

PC

2

M

2

M

3

M

1

4

3

2

1

+24 V DC

+24 V DC

Start

Inputs

Outputs

PLC

I0.1

I0.3

I0.4

Q2.0 Q2.2

Q2.4

Q2.6 Q3.0

0 V

0 V

Figure 10.2  Conveyor system for an assortment of objects by pairs.

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Industrial Applications 

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contains an object, and the next coming object has the same color, then the buffer M

2

 must be 

moved to an empty position or to a position with an object of different color. The arrival of objects 

is random but suppose that it is impossible to find more than four objects of the same color. The 

conveyor system starts to operate after a momentary signal from the push of a START button and 

stops similarly through the push of a STOP button. Write the required program for a PLC.