Re: [CAD_CAM_EDM_DRO] Compumotor Plus stepper drive

hi Carey,

unfortunately while a resolver (a two-phase field syncro) can be connected
as a motor and will produce a little power, a two-phase stepper cannot be
connected to function as a resolver. the resolver has a reference phase
(a single-phase winding on the armature) while the stepper motor uses a
permanent magnet armature (at least in the type of stepper motors discussed
here for machine drives). there is a lot of work (and some patents issued)
on detecting the position of a stepper armature without additional encoders
or windings, but there is no way to connect a stepper to a resolver input,
since there is no output of the stepper when stopped. the resolver, however,
works when stopped due to the ac excitation of the armature.

yes, when equipped with a hi-resolution position sensor (such as a resolver,
or encoder) there is no distinction between a stepper motor and a brushless
dc servo motor.

-ron

On Sun, 2 Jul 2000, Carey L. Culpepper wrote:

> Darrell: Read my lips! I said that I spent a day pouring through the
> manual that is pretty clear that these are stepper drives and are ,in
> fact, designed to drive Compumotor steppers with built in
> resolvers.Better yet, why don,t you pop into the their web-site and see
> for yourself. www.compumotor.com/literature.htm then click on user
> guides and then Compumotor Plus user guide.Be advised that they do call
> it a " servo system" but read on. A servo system using resolver equipped
> stepper motors.A very impressive setup,if you have the right motors.
> Thinking about the possibility of putting a stepper motor in place of my
> encoder and using it as a resolver. If only I knew how to wire it. Let
> me know what you think. Carey
>
> Darrell wrote:
>
> > Stepper motors do not have resolvers. Some servo motors have
> > resolvers. That
> > driver is for running servos with step and direction signals.
> > Darrell
> >
> > ----- Original Message -----
> > From: Carey L. Culpepper <mr.c@...>
> > To: <CAD_CAM_EDM_DRO@egroups.com>
> > Sent: Saturday, July 01, 2000 7:20 PM
> > Subject: [CAD_CAM_EDM_DRO] Compumotor Plus stepper drive
> >
> >
> > > I have spent the whole day trying to get a Compumotor Plus drive to
> > run
> > > a motor with step-direction inputs. I downloaded the manual and have
> >
> > > gone through it several times. The drive has a computer on-board
> > that
> > > sets everything. Everything is set through serial port commands
> > > including current rating and microstepping resolution. The problem
> > is
> > > that the units are designed to be used with motors with built in
> > > resolvers.The manual specifies that it will not accept encoder
> > input.If
> > > the motor gets a pulse, it is expected to turn a step. If it doesn't
> > it
> > > keeps trying or gives an error message. It operates just like a
> > servo
> > > motor and is tuned accordingly with a series of switches or through
> > the
> > > RS232. I have gone through the manual several times trying to find a
> >
> > > command that would let me run it without the resolver. All I found
> > were
> > > commands to set the amount of allowable error. So, I shut it down
> > and
> > > got my screwdriver and had a "look under the hood". Three PCB,s one
> > with
> > > the computor circuitry,one small board with the display and tuning
> > > switches, and the power supply/driver board. I found three jumpers
> > > together on the computer PCB.
> > > My question is this: Is it possible to run these drives without the
> > > resolver input? Anyone familiar with these units. They are very
> > > sophisticated. I am impressed. If only I had motors with resolvers.
> > > These are made to be run closed loop.
> > >
> > >
> > >
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