arpschuino.fr

Whilst testing the steppermotor function, I noticed something strange.
When I change the DMX value quickly, the motor moves fine.
But when I ramp it up slowly, the motor behaves eratically, going back and forth.
It looks like the problem only occurs when I ramp up (from 0 to 255) and not when I ramp down (from 255 to 0).
Any idea what could be the cause of this?

https://youtu.be/0EKgoE_yOxc

This back and forth is not at all normal!
I must admit that the dynamic speed management is not perfect, there are somes steps. This is the next project I plan to take care of.
But even with the current imperfections you shouldn't have these problems... Can you make a screenshot of your configuration please?

Hi Jacques,

I don't see how I can add a picture, so here are my setting for motor 1 (or 0):
Mode: stepper
Stepper to config: 0
Active: yes
Steps per revolution: 400
Revolutions per minute min/max: 100/2400 (I have speed set at DMX value 150, so about 58%)
Number of revolutions: 13,5 (There's a 1:27 reduction on the motor and I wanted it to do 0,5 turns)
Uninverted
Action: perform
Input: 8 bits

I'm using an external stepperdriver set at 1,36A RMS and 400 pulses/revolution

The strange thing is that it only does it when the DMX value is increased, not when it is decreased,

Indeed it is very strange...
I'll try to reproduce your setting tomrow at home. i said I ll try because I am not sure if I'll get enouth time because of my family life !
There may be a resonance problem (look on the net for articles about stepper resonance). To find out, try another range of speed values (for example 10/400) to see if the problem is still there.

I tried several ranges. 1-100 (when I use 1, the stepper will barely move, unless I set the speed at maximum), 10-100, 25-500, 50-500, 100-1000 etc. It does the same thing on every setting.
I now have it at 50-550, that seems to be a combination where I can actually set the speed at maximum (255), without the motor stalling when I ramp it up as fast as I can.

I understand, the interface is in French...
When you write an answer, at the bottom, you can click on "fichiers joints" to find your file.
Then, you have a button "insrer dans le message" so that the image is inserted in your message.

Ah, I see. Thanks!
I did have the forum translated to English, but missed the attachments-tab.

Maybe this will be of help when fault finding: I just tried to invert the steppermotor. It seems the problem is gone when I do that.

What do you mean by "invert the stepper motor" ?