stepper motor drivers from phytron in APS 'format'

[Tim Mooney <mooney@aps.anl.gov>]

Ok, I can see my last message was a little terse.  Here's a synopsis of
recent traffic on the TWG email list:

Apparently, Phytron, in the person of Wahid Lahmadi, who presumably
works for Phytron, plans to discuss an alternative to the Advanced
Control Systems StepPack on Friday 1/12 at 10:00, in the conference
room of LOM 434.  This discussion is sponsored by Dr. Markus
Schwoerer-Bhning (HP-CAT).  The objective is to get input from people
at APS and, no doubt, to get a little market information and do a
little advertising.

I don't know if the proposed Phytron system is modular.  If it is, I
don't know if the modules are intended to be interchangeable with ACS
StepPack modules (I'd guess not -- if we want that feature, we should
argue for it).  I don't know if Phytron is up to speed on the RS422
noise vulnerability issue we had originally with the StepPack (control
lines disconnected at the VME crate, and a powered off VME crate with
control lines connected to the StepPack, both resulted in motors moving
in response to ambient electronic noise).  I don't know if Phytron
intends to support all possible motor-cable wirings.  It's possible
they've only committed to the DB25 and Elco pinouts, thus far, and are
hoping we will provide enough information to ensure their system is
interchangeable with a StepPack.  I also don't know what current range
they're aiming at, whether or not they have motors that can't be driven
by an unmodified ACS StepPack, whether they have a holding-current
strategy, etc.  I also don't know if Phytron is talking to ACS.

If you have practical experience with motors, and particularly with the
StepPack, you might be able to do HP-CAT (and other new CATs as well) a
favor.  It sure is a lot easier to fix hardware problems if you can
identify them before the hardware is mass produced and deployed.

Tim Mooney