Introduction to Industrial Automation

Figure 10.12  Combined operation of two conveyor belts.

---

Industrial Applications 

◾

 

393

pressing of the button b

0

. The indication light H

0

 is turned on during the cleaning procedure. 

After making a diagram of the connection of the I/O devices to a PLC, write the required program 

in the LAD language.

10.15   Driving a Step Motor Through a PLC

Step motors are electric motors of specific construction for high-precision positioning applications 

in complex machines. In particular, step motors are brushless DC motors that rotate in discrete 

steps usually of 1.8° and in both directions, while they can operate in full or half step mode. Step 

motors require an electronic circuit called a controller or driver to energize the motor phases in a 

timely sequence to make the motor turn. As shown in Figure 10.15, the stepper driver accepts the 

following four control signals:

+24 V DC

+24 V DC

0 V

Resistors

Start/stop

Cancel

0 V

PLC

I2.0

I2.1

Q1.0

Q2.0

Q3.0

C

Inputs

Outputs

Preheating

wait 3 min

Figure 10.13  I/O device connections to PLC for the application of Section 10.13.

LS

1

LS

2

Up and down

limit positions

M

H

b