Introduction to Industrial Automation

Figure 10.9  Two milk tanks with automatic filling.

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Industrial Applications 

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10.11   Traffic Light Control of a Complex Intersection

At an intersection between three towns, as shown in Figure 10.11, the traffic lights are controlled 

by a PLC. Their operation is based exclusively on timers, i.e., there are no traffic sensors. The 

green left light flashes every second for 10 seconds. All the other lights operate according to the 

bar diagram. The cyclic operation of the lights starts/stops through the rotary switch RS

0-1

. It is 

recommended that the required PLC program be written in Boolean or LAD language.

S

4

S

1

S

2

S

3

P

1

1

2

3

4

5

6

P

2

P

3

P

4

P

5

P

6

Reinser

tion

Reje

ct

Repairing station

P

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