Re: stepping motor driver, 8-pack, Phytron-ECT

[McNulty <mcnulty@aps.anl.gov>]

Related comments:

We use ACS stepper drives extensively in Sector2. While both the
unipolar and bipolar
half/full-step drives are very reliable, we've had very disappointing results
with ACS microstepper drives. They work fine when they do work and have
not given us
many noise headaches, but they are very sensitive to power-cycling, hot-plugging
motors, etc., i.e. the usual things one should not do but which still occur.
In particular, the microstepper drives frequently fail if one does not switch
off their motor current switches before switching off or on the
ACS Step-Pak crate power. The failure mode usually manifests as a 'busy' light
that either always stays on or off, and no stepper function. Apparently
the failures
involve the large nonstandard chip in each module, which is easy for ACS
to replace
but difficult to troubleshoot on-site.

When microstepping is required we've resorted to Compu-Motor OEM units
which are
very quiet, don't need extra cooling for 6A/phase motors, and are
utterly dependable
(they should be, they cost much more).

On the other hand, in addition to ACS unipolar drives we are very happy with
their bipolar units for our growing number of low-current two-phase
motor-driven stages, e.g. Newport's MFN series, in combination with
current-limiting resistors. Unipolar dives will not work with such
(4-lead) motors.
One case in point: we use a tiny 8-mm diameter 24-step 2-phase motor
rated at
60 mA/phase (the dropping resistors are 1K ohms!).

-- Ian



Markus wrote:
> 
> On Mon, Feb 19, 2001 at 02:42:04PM -0600, Mark Rivers wrote:
> 
> >
> > Note that the Lincos drivers look nice, they are linear (quiet) and they can
> > microstep up to 20 microsteps/step.  However, they can only drive 2.5 amps
> > per phase.  If you want to drive larger motors you need to use the ZSO
> 
> But, they can run down to 0.25 Amps without burning motors
> 
> > drivers.  However, those are choppers, so they will probably not be
> > electrically quiet.
> 
> Phytron claims that using appropriate shielding of the cables avoids noise.
> I have not heard such about the ACS microstepper.
> 
> >
> 
> StepPack runs hot at > 5 Amps running current, requires additional cooling
> which is provided within the chassis of Phytron. For StepPack it takes extra
> space.
> The same is true for the power supply. ACS PS takes as much space as a driver
> rackmount, therefore, requires taller racks. ACS PS supplies 25 Amps, while
> Phytron build-in PS provides 20 Amps for the ZSO.
> 
> > On our beamline >75% of the motors are more than 2.5 amps/phase, so ZSO's
> > would be needed.
> >
> > Note also that on the Step-Pak you can mix and match different drivers
> > (microstepping, unipolar, bipolar) in a single chassis.  I don't think you
> > can do that with either proposed Phytron unit, so you would need a complete
> > rack to service a single microstepping motor.
> >
> > If the issue is price we should we ACS to bid against Phytron and give us
> > quantity discounts like they are.  Their single unit prices are no better.
> 
> The issue is price and quality which is not well matched concerning ACS drivers.
> 
>  Markus
> 
> --
> Dr. Markus Schwoerer-Böhning
> Carnegie Institution of Washington, High Pressure CAT
> c/o Argonne National Laboratory, Bldg. 434-E
> 9700 S. Cass Ave.
> Argonne, IL 60439
> 
> Tel.: (630)-252-0411
> Fax.: (630)-252-0496
> e-mail: markus.schwoerer@anl.gov