Re: [Ext]How to use Optics Slit records with absolute encoders?

[Jesse Hopkins via Tech-talk <tech-talk at aps.anl.gov>]

Hi Mark,

 

Thanks, that’s exactly what I needed!

 

All the best.

- Jesse

 

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Jesse Hopkins, PhD (he/him)
Director, BioCAT

Sector 18, Advanced Photon Source

Research Associate Professor, Illinois Tech

 

From: Mark Rivers <rivers at cars.uchicago.edu>
Date: Thursday, May 15, 2025 at 10:21 AM
To: Jesse Hopkins <jhopkins1 at iit.edu>
Cc: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: [Ext]How to use Optics Slit records with absolute encoders?

Jesse,

 

The motor record does change the OFF field and not DVAL as long as you set the FOF field to Variable.

 

Mark

 

Sent from my iPhone

On May 15, 2025, at 10:12 AM, Jesse Hopkins via Tech-talk <tech-talk at aps.anl.gov> wrote:



Hi Mark,

 

Thanks for the suggestion, the offset parameter is quite useful here (even in just getting the scales to agree, since the vendor seems to have applied them a bit inconsistently). A few months ago I did set up some slit pseudomotors with the CSAxes in the GALIL, and it worked. What I ran into however is that the ease of use wasn’t great, as setting slit size and position values required manually setting component motor positions (in this case I’d have to do it via the offsets). Since I’m not doing fly scans or similar with the slits, precise synchronization isn’t as important for me, and the Optics module Slit records provided a high convenience level.

 

I guess the follow on based on what you said is whether there’s a way to get the motor record with absolute encoders to change the offset value when the position is set, so that standard approaches would work in a transparent fashion?

 

All the best.

- Jesse

 

----
Jesse Hopkins, PhD (he/him)
Director, BioCAT

Sector 18, Advanced Photon Source

Research Associate Professor, Illinois Tech

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Mark via Tech-talk <tech-talk at aps.anl.gov>
Date: Wednesday, May 14, 2025 at 9:46 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: [Ext]How to use Optics Slit records with absolute encoders?

Hi Jesse,
To move the motor record readback for an axis using an absolute encoder,
the motor record OFF field can be used.
Here is a short example.
1.  Move the motor to beam centre.
2.  Adjust motor record OFF until the readback becomes 0

CSAxis will provide greater motor synchronicity over the slits
database.  Note the Galil EPICS driver supports the motor record OFF
field for GalilAxis (real motors), but not for GalilCSAxis (coordinate
system motors).
Kind regards,
Mark Clift.

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