Stepper motor to turn the top of a crane

Hello Everyone,

I am kind of lost in the amount of stepper motors there are and what would be the best for my needs.

I am building a crane. The top of the crane needs to rotate. I want to be able to rotate the crane to the left and right. I am connecting the motor to a PLC (Siemens Logo). So what I need is a servo/motor that:

Can turn left and right (might need an additional driver)
Able to mount the crane-head to it
Can turn at least 750 gram
Can be connected to the PLC (12V)

I hope you can help me with the right servo. I am absolutely lost.

Thank you.

Kind regards.

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Hello @mrbaselier and welcome to the forum!

You have an interesting project but also a lot of things are unclear, or at least not written here.

Some questions from my side:

  • Are you sure that you need stepper motor? Stepper motor is usually used if the angle has to be very precise. Since this is a crane, is the position really important to you? This tutorial should help you to make a decision: Basics: How Do I Choose an Actuator | RobotShop Community

  • Able to mount the crane head to it? What are the dimensions that you need? I guess the shaft dimension is important for you.

  • Can turn at least 750 grams. You need to calculate torque you need. Maybe this can help: Drive Motor Sizing Tutorial | RobotShop Community

  • Can be connected to the PLC (12V). OK, voltage is clear, but which communication interfaces does this PLC have? Or you want to control it simply with inputs and outputs?

Thank you.

Hello Igor,

Thank you for taking the time to answer this (vague) question. As I read I have a lot of things to consider. I guess I want to:

Turn the crane head left and right and be able to stop at a specific position.
With another motor I want to control the cable/wrench

Guess I do not specifically need stepper motors in this case?

I will try to calculate the torque. This is new to me so I might need a little help here. Thank you for the hyperlink!

I want to controll this by connecting them to a 12V Siemens Logo PLC. So with the inputs and outputs of the PLC.

Thank you again for your answer.

Kind regards!

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Hello @mrbaselier !

If you want to control this setup via PLC input/outputs, then first that comes to my mind is to use a microcontroller with motor driver to control the motors.

So your PLC would set output bits which microcontroller will see as inputs (you need to take care of the voltage levels here since PLC is usually 12/24VDC while microcontrollers usually work on 3.3 or 5 VD) and then you have software on your microcontroller which will decide what to do with motors based on the inputs. Motor driver is there to control the voltage on the motors.

This is the first thing that comes to my mind, but there are different solutions also, which mostly depend on your choice of the motors.

Hello Igor,

You are an amazing help!! Thank you so much for your valuable input!! I will take that in consideration and update this topic if I have any more questions.

Have an amazing day.

Kind regards!

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Hi again.

I think this article can be helpful for you: Motion Control / Positioning Control for PLC using Arduino

Although here is Modbus protocol is used to connect Arduino and PLC. Not sure if your PLC supports Modbus?

Yes, it does support Modbus so that should work :slight_smile: I will read the article tonight! Thank you so much for all your effort and help. Greatly appriciated!

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You are welcome :slight_smile: