Introduction to Industrial Automation

Figure 10.14  Tank-elevator system for chemical cleaning of metallic objects.

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  Introduction to Industrial Automation

Step. For each pulse applied to the step input of the driver, the motor turns one step ahead. For 

a series of pulses the motor turns by an equal number of steps. The frequency of the pulse 

waveform defines the rotation speed of the step motor.

Direction. A logic high signal applied to the direction input of the driver determines one direc-

tion, while a logic low signal causes the opposite direction of rotation.

Full half step. The full or half step mode of rotation is determined by a logic high or low signal 

respectively.

Enable. A logic high signal applied to the enabled input of the driver enables the motor to rotate 

if the previous three signals have been applied. A logic low signal disables the step motor that 

cannot rotate, even if the previous three signals are applied.

The above signals can be produced from a PLC equipped with a suitable digital output mod-

ule. Write a program in Boolean language so that the following operations are achieved:

  1. With the press of button b

1

 and the RS switch open, the motor rotates left with a full step.

  2. With the press of button b

2

 and the RS switch open, the motor rotates right with a full step.

  3. With the press of button b

1

 and the RS switch closed, the motor rotates left with a half step.

  4. With the press of button b

2

 and the RS switch closed, the motor rotates right with a half step.

The desired speed of rotation corresponds to a pulse frequency of 25 Hz.