PLC + Power DC Motor + High-Power Motor Driver

Hi. I have PL 1456 High Power Motor Driver 24v23 CS.

I want to use it to drive 24VDC, 6A (20A Peak) Brushed DC Motor
(Appr. 40 W, 1.17 Nm, 4000 RPM) with 3 channel optical encoder.
The motor will stir some liquid with a shaft and propeller.

I have a 24VDC PLC with digital Input ports, digital output ports, analog input and output port. It has separate 50Khz pulse counter in three output ports, too.

User will enter motor speed in a range 100-1200 RPM on HMI screen.
PLC will evaluate RPM and PWM signal cyle (Hz) using linear function and send it to Motor Driver’s PWMH pin.

Could you please confirm that the given connections bellow are true?

Connect encoder Ch.A, Ch.B and index (or Z) to PLC’s High Speed Counter (HSC) group
input ports IP0, IP1, IP2 respectively.

From power supply (220VAC-24VDC, 20A)
24VDC + --> Motor Driver’s V+
24VDC - --> Motor Driver’s GND

DC Motor A output pin --> Motor Driver’s OUTA
DC Motor B output pin --> Motor Driver’s OUTB

Motor Driver’s PWMH pin --> PLC’s High Speed Pulse Output Group (HSO) --> QP0 (Output port)
Motor Driver’s DIR pin --> HSO --> QP1 (Output port)

Thanks in Advance.:grinning:


The maximum logic level on that motor driver is 5.5V so if your PLC uses 24V logic signals, you will need something like a logic level shifter or a set of voltage divider resistors to change the signal level. That driver board does not have any encoder inputs, so you will need to handle those with your PLC, but I cannot say for certain whether the specific connections you mentioned will work. The supply you mentioned sounds OK. OUTA and OUTB are outputs from the driver and inputs to the motor, but I cannot tell from your description if that is how you intend to use them. The PWMH and DIR pins on the driver board are digital inputs and your connections sound like they could be correct (if your PLC logic voltage is less than 5.5V), however we are not familiar enough with that PLC to say for certain.


Thank you for your reply.

  1. I’m familiar with 24 5 V logic signals difference.
    PLC producer strongly advices using a resistor.
    So, I use 2.2 KOhm, 2W resistor to prevent any inconvenience.

  2. I also made a contact about encoder connections to the producer. It is Ok.

  3. Actually, I want to learn what happens when PLC sends a PWM Pulse Signal to the motor driver.
    Does it change the voltage and apply it to OUTA and OUTB internally?
    Does PWM signal have a linear relation to motor voltage output?
    For example, 0 VDC <–> 0 Hz (PWM pulse)
    24 VDC <–> 40 Khz. (PWM pulse)


The motor power is determined by a fixed frequency, variable duty cycle PWM signal. Generally, using something like a 50% duty cycle PWM signal will result in the motor being driven at about 50% of the input voltage. Depending on your motor and PWM frequency, though, the relationship might not be completely linear.