On Monday 16 April 2018 20:11:46 jeremy youngs wrote:

> The 5i25 will work with my existing breakout boards if I'm
> understanding correctly.  And a spinx1 will get me to an analog +-10
> that I can flip flop for reversal. I'm thinking 5i25 and softdmc
> should get me where I want to be. And be expandable later on . Can the
> 5i25 output a 0-5 v analog, it would be simpl to make a 2 gain
> follower with op amp.

No, the closest it can do is pwm or better yet, pdm, see the docs. 
Reversal, if you want zero speed to be zero pdm, will need a separate 
gpio for signalling the spinx1 or the pwm-servo amplifier to reverse. 
Theoretically, a 50% pwm could be use as zero speed, but requires very 
accurate sensing at the creep speeds, which has always bothered me so 
I've never explored the -5-0+5 options. Perhaps someone who does have 
such a setup can comment?
One other item I'd point out is that the timing of an opto-isolator will 
totally wreck the linearity of the control. Rip it out on that pin of 
your BoB, or get some sainsmart BoBs. They only have the opto junk in 
the inputs, so you may have to bypass the 2 used for the A/B signals 
from the encoder if its a hi rez encoder.

I use pdm mode, which works well on the spindle motor of the mill, 
turning it at 20 rpm when its in between gears so the gear meshing when 
I turn the knob is silent and effortless, with the spindle running. 
There, the pdm is fed to the input of one of Jon's Pico Systems 
pwm-servo amplifiers, which drives that 90 volt motor rated at a horse 
at 2200 spindle revs in OEM configuration, to around 2hp at 3000 spindle 
revs. My encoder is not on the spindle, but on the motor, so that 20 rpm 
is plenty stiff enough to move the motor. Hal takes care of the scaling 
so the spindle tach is accurate in either gear.

I am assuming you are controlling a vfd with a spinx1?  Works great on my 
Sheldon lathe that way. No spinx1 is needed on the mill or the 
mini-lathe with their PMDC motors, its all done in the pwm-servo amp.

> Sorry to be an ask hole I would like to figure 
> this out and order tomorrow. Thanks for input

Good luck, Jeremy. And keep us posted, plz.
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