Introduction to Industrial Automation

10.9   Automated Filling of Two Milk Tanks

In a milk factory, a PLC automatically fills two milk tanks. As shown in Figure 10.9, each milk 

tank has two floater switches, up and down, which provide the signals “fill” and “empty” respec-

tively. The specifications of operation are the following:

  1. The automatic filling of the tanks is energized/de-energized by pressing the ON and OFF 

buttons respectively. The indication lamp H

0

 shows the operation state.

  2. Only one milk tank may be filled at a time. If the two tanks are simultaneously empty, then 

the first tank fills first.

b

(1)

SL

Coins box

M

Balls box

H

1

,

F

1

, F

2

F

5

F

6

F

3

, F

4

H

2

F

1

H

1

H

2

F

2

F

3

F

4

F

5

F

6

(1)=Coins return place

+24 V DC

+24 V DC

0 V

0 V

SL

C

(M)

b

PLC

I0.0

I1.0

I1.1

I1.2

I1.3

I1.4

I1.5

Q1.5

Q1.4

Q1.3

Q1.2

Q1.1

Inputs

Outputs