How to use Optics Slit records with absolute encoders?

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

Hi folks,

 

Now that I’ve got the absolute encoders working on my slits, I have a new problem. We’ve been using the Optics module Slits records to calculate and control slit center and gap based on the pairs of slit blades. The way these work is they reset the motor positions when you set the center or gap, so that the calculation of center/gap matches the setpoint you provide. Unfortunately, this doesn’t work with our slit blades with absolute encoders. As you would expect if you set the center position (for example) it resets the individual slit bade drive positions but not the readback positions, since those are based on the encoders.

 

Does anyone have any suggestions on how to use the Slit records with absolute encoded motors?

 

One possibility that occurred to me was creating a soft motor layer between the slit bade and the slit definition, that applies an offset to the slit position. When you set the position of this soft motor it would then recalculate the offset between the hard motor and the requested set position and act appropriately. I imagine this would look something like the TransPos.db record in the motorApp, but I don’t’ think that quite gets there?

 

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