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PostPosted: Sat Mar 10, 2012 11:06 am 
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Phidgetly

Joined: Mon Feb 13, 2012 10:31 pm
Posts: 31
I'm connecting an STP-58D2017 motor to a 1062. It works, but very slowly. 28 rotation per minutes even with acceleration set to the max (8859.375)

Could attaching the wires the wrong way explain that behavior? It goes forward and backward as expected.

I found a phase table for that motor that shows the following sequence:
They have a diagram that shows that 1 coil is AB and the other A'B'

step A B A' B'
1: 1 1 - -
2: - 1 1 -
3: - - 1 1
4: 1 - - 1

Trying to map this to the 1062 table I came up with the following wiring
(I took all the entries in the 1062 table that had 2 powered poles, and offset the starting point until I found a sequence where the next full step had one pole in common with the previous one)

motor 1062
A D
B B
A' C
B' A

As I said, it works, but slow. Any idea?
The motor data shows that A A' is one coil, and B B' the other.


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PostPosted: Sat Mar 10, 2012 11:42 am 
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Phidgetly

Joined: Mon Feb 13, 2012 10:31 pm
Posts: 31
One thing I was forgetting to set was max velocity.
But even setting it to the max (383.25) I only get about 56 rotation per minutes.

Shouldn't I get about 48 full revolution per second at max velocity?
My reasoning which you are welcome to make fun at:

383 half step per second
191 full step per second
4 step to a full revolution, so about 48 full rev per second


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PostPosted: Mon Mar 12, 2012 7:12 am 
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Human-Cyborg Relations
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Joined: Tue Sep 27, 2011 2:37 pm
Posts: 407
Location: Calgary
From what I can see that motor has a 1.8 degree step angle. That means that 191 full steps per second is 343.8 degrees per second or approximately 57.3RPM. At 1.8 degrees per step there are not 4 steps per full revolution, more like 200.

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Brian Burley
403-282-7335 ext. 6003
support@phidgets.com


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PostPosted: Mon Mar 12, 2012 9:21 am 
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Phidgetly

Joined: Mon Feb 13, 2012 10:31 pm
Posts: 31
burley wrote:
At 1.8 degrees per step there are not 4 steps per full revolution, more like 200.


Oops. Nothing like starting with the wrong assumption! :oops:
So about 1 revolution per second is the max I can expect from 1.8 degree step angle motors then.

Just by curiosity, why the order of magnitude difference in max velocity between the 1062 (about 191 step / sec) and the 1063 (about 2048 step / sec)
Is it a limitation forced by the nature of the motor (unipolar vs. bipolar) or is it design choices on the boards?


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PostPosted: Mon Mar 12, 2012 12:08 pm 
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Lead Developer
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Joined: Mon Jun 20, 2005 8:46 am
Posts: 2644
Location: Canada
It's a firmware limitation - the 1062 needs to manage 4 motors at once, whereas the 1063 only has to manage 1. Also, the 1063 switches into full stepping mode at the faster velocity, so you get more velocity per instruction.

-Patrick


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