Stepper motor continuous run

[Mr. Ro Bot]

I've got an SLC500 running a 1746-hstp1 controlling a stepper motor. What's the best way to set the motor to run continuously?

I only see Jog, Relative, and Absolute move options. The best I've come up with is just running the motor in Jog for a desired time or try to do blended moves. Looking for an simpler option if there is one


Thanks!

 

[b4umusic]

Jog command can run stepper motor continuously, Turn bit on to enable jog and turn bit off to stop

 

[Mr. Ro Bot]

I'm running a Nema 34 motor at 48Vdc and it's rated for 12nm, but it seems like it's got almost zero torque.

I've got the motor running 800 steps per revolution, and a speed of 10,000 PPS. But I can literally put my finger on the shaft and stop it. Any suggestions?



http://https://www.omc-stepperonline.com/download/34HE59-6004D-E1000_Torque_Curve.pdf

 

[chavak]

You will have either dip switches or rotary switches on the stepper driver to adjust your motor current, you need to set it as per your needs

A quick peek on the manual found these

The first three bits (SW1,2,3) of the DIPswitch are used to set the dynamic current

 

[b4umusic]

You are running servo motor at a speed of 750 RPM (10000pps/800steps/rev=12.5rev/s=750RPM), from the torque curve you can see at 750RPM torque drastically reduce, so in order to get more torque you have to reduce the speed of the motor, try reducing speed to 300RPM by reducing 10kpps to 4kpps or increase micro stepping to 2000.
Remember stepper motors are suitable for low speed/high torque applications, At zero speed stepper motor give max torque as you can see in the torque curve.

 

[Mr. Ro Bot]

My current setup uses an AC motor running at 1750 RPM. It works great, but I need to sync multiple motors and I need the ability to have a "Jog to home" after the motors stop their main run.

From the look of things I don't think a stepper motor would work for my application at that high of a speed.

What do you suggest? Would a servo motor be any better? I'm not familiar enough with servo or stepper motors, but I've had some equipment that came w/ servo motors that pulled tremendous loads at a good pace.

 

[b4umusic]

Yes, Servo motor will work fine for High Torque/High Speed applications but it will not be as economical as stepper motors.

 

[Mr. Ro Bot]

Are there any Servo Motors that work best w/ SLC500 plcs? The program I'm using is pretty straightforward. Stop/start. Run at constant speed, then jog to home when stopped.

Does allen bradley make a servo motor control for the slc500s or would it have to be separate?

 

[tdoa]

Addind encoders to your current motors wont work?

 

[alan_505]

Allen Bradley did make a servo module for the SLC 500's but it has been obsolete for quite a while (1746-HSRV discontinued March 2012).

 

[Mr. Ro Bot]

Addind encoders to your current motors wont work?

I'm running four motors at different speeds and loads. I'm trying to keep them synced at their specific RPMs while the loads fluctuate while running. Right now I have 3 DC motors and 1 AC motor. The issue I've run into is as the load on one motor increases the RPM lags, which starts to throw them all out of whack.

You think it might be easier to add encoders and drives to help instead? I've programmed VFDs but I've never included encoders for feedback before.

I was hoping going to stepper motors would allow for precise speed control w/ all the motors, but it's obvious to me now that they're just not strong enough for this application.