Industrial Applications
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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
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