Introduction to Industrial Automation

Figure 10.10  A group of processing and repairing stations.

+24 VDC

+24 VDC

0 V

0 V

RS

0-1

G

R

GA RA GP RP GR RR

PLC

I1.3

Q1.0 1.1

1.2 1.3 1.4 1.5

1.6 1.7

Inputs

Outputs

Output Light

10 s

20 s

20 s

= Red light

= Green light

Q1.0

Q1.1

Q1.2

Q1.3

Q1.4

Q1.5

Q1.6

Q1.7

G

GA

RA

GP

RP

GR

RR

R

GA 

= Green Amiens

Light color

Destination place

G

R

Rouen (R)

Amiens (A)

Paris (P)

RA

GA

RR

GR

RP

GP

Figure 10.11  Traffic light control of a complex crossroad.

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  Introduction to Industrial Automation

10.12   Combined Operation of Two Conveyor Belts

The two conveyor belts M

1

 and M

2

, as shown in Figure 10.12, transfer boxes toward a packag-

ing machine. Each has a photocell sensor for counting the transferred boxes. Write a program 

in Boolean language so that the arithmetic difference of transferred boxes remains less than ten. 

When this condition is violated, the conveyor belt, having transferred more boxes, must stop until 

the difference is null, and then the overall process should start again.