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<== Date ==> <== Thread ==>

Subject: Re: Motor home status
From: Pete Jemian <[email protected]>
To: Mark Rivers <[email protected]>
Cc: [email protected]
Date: Wed, 13 Aug 2008 11:21:47 -0500

I agree.


Mark Rivers wrote:
I think we should keep ATHM to have the "at home" meaning.  But for
controllers like the PMAC and XPS that use the asyn motor drivers it is
easy to add a new PV containing the "homed" status.  It will mean making
a new medm screen, but I think that is the best way to do it.

Mark


-----Original Message-----
From: Pearson, MR (Matthew) [mailto:[email protected]] Sent: Wednesday, August 13, 2008 10:51 AM
To: Mark Rivers; Ron Sluiter; Joe Sullivan; Tim Mooney; Pete R. Jemian
Cc: [email protected]
Subject: RE: Motor home status



Hi Mark,


Thanks. I agree we should stick with 'at home', especially if a lot of
controllers don't have the 'homed' concept. With regards to the controllers that do have that concept, should the
drivers use ATHM to mean 'at home'? The PMAC driver currently doesn't,
but the XPS driver does. Do you think we should bring the XPS driver in
line with the PMAC driver? (or vice versa?)


From the users point of view it's slightly confusing. At Diamond they
are used to seeing motors in a homed state, regardless of position. Our
XPS motors always tend to look 'un-homed', because they've been driven
away from home position.


I don't think you can infer "at home" from the position. What if the motor is a stepper with no encoder and it lost steps sometime after being homed? It might not really be at home when the position says it is.


Good point, I forgot about that one.



Cheers, Matthew

Mark


-----Original Message----- From: Pearson, MR (Matthew) [mailto:[email protected]] Sent: Wednesday, August 13, 2008 4:37 AM To: Mark Rivers; Ron Sluiter; Joe Sullivan; Tim Mooney; Pete R. Jemian Cc: [email protected] Subject: Motor home status


Hi,


At Diamond we're currently using several motor controllers, including
the OMS (58 and MAXv), the Delta Tau PMAC (PMAC2-VME, Geobrick) and the
Newport XPS.


The motor record has a field called ATHM, which is set to 1 when the
motor has hit a home switch.

The OMS and Newport drivers use this field correctly, in that ATHM is
set to 1 when the motor is at home position (and is 0 otherwise).
However, the PMAC driver retains the ATHM status when moving away from
the home position - it actually means 'homed' for this driver, rather
than 'at home'.

Most of the motor control at Diamond is performed using the PMAC driver,
so everyone here has become used to this convention. It is arguably more
useful to have a 'homed' status, rather than 'at home'. Especially since
the 'at home' status can be inferred from the position (once it is homed
of course).


Is it the case that every other driver apart from the PMAC driver obeys
the ATHM status? I was considering changing the XPS driver to bring it
in line with the PMAC driver (for the benefit of our beamline users
mainly). However, if every other motor controller driver out there obeys
ATHM, then changing another one to do something different probably isn't
ideal. In this case, we'll probably just leave it as it is.


Any thoughts on this? Or info on other motor controller drivers?

Regards,
Matthew

Dr Matthew Pearson
Software Systems Engineer
Diamond Light Source Ltd
Diamond House
Chilton, Didcot
OX11 0DE
Tel: +44 (0)1235 778538
(58
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<DIV><FONT size="1" color="gray">This e-mail and any attachments may
contain confidential, copyright and or privileged material, and are for
the use of the intended addressee only. If you are not the intended
addressee or an authorised recipient of the addressee please notify us
of receipt by returning the e-mail and do not use, copy, retain,
distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual
and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any
attachments are free from viruses and we cannot accept liability for any
damage which you may sustain as a result of software viruses which may
be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in
England and Wales with its registered office at Diamond House, Harwell
Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United
Kingdom
</FONT></DIV>

-- ---------------------------------------------------------- Pete R. Jemian, Ph.D. <[email protected]> Beam line Controls and Data Acquisition, Group Leader Advanced Photon Source, Argonne National Laboratory Argonne, IL 60439 630 - 252 - 3189 ----------------------------------------------------------- Education is the one thing for which people are willing to pay yet not receive. -----------------------------------------------------------



References:
RE: Motor home status Mark Rivers

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