RE: Behavior of the soft motor's DINP field

["Pearson, Matthew via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Abdalla,

 

Can you try setting the LOCK field to 1 in the soft motor, and see if that resolves the issue?

 

I’m not sure why the soft motor VAL sync issue is happening, but LOCK will prevent VAL being synced with RBV at the end of a move, which is sometimes necessary. We have set LOCK=1 on our slit control applications, as part of the mechanism of preventing gap/center drift.

 

Cheers,

Matt

 

 

From: Abdalla Ahmad <Abdalla.Ahmad at sesame.org.jo>
Sent: Sunday, January 7, 2024 7:07 AM
To: Pearson, Matthew <pearsonmr at ornl.gov>; Torsten Bögershausen <Torsten.Bogershausen at ess.eu>; Peterson, Kevin M. <kmpeters at anl.gov>; tech-talk at aps.anl.gov
Subject: [EXTERNAL] Re: Behavior of the soft motor's DINP field

 

Hello Mathew

 

Thanks for the feedback. Again, sorry for the misunderstanding but the real issue is that the soft motor reaches the corresponding position (set in the RBV), but the difference that I mentioned in my first email is that the VAL is a bit different than the RBV. Here I attached two screenshots, one with DINP set and the other without DINP. Somehow the soft motor does not SYNC the VAL with the RBV, I tried controlling the SYNC field through the database using various technique but nothing works. Up to now, removing the DINP field seems working fine but I don't know if this would cause an issue.

 

Please note that I am using the exact implementation as in the sum2Diff.db in the motor record except for simpler equations of course, I am thinking there might be something to investigate in the motor record and soft motor sources, so If anyone can elaborate on this topic it is really appreciated.

 

P.S.: One of the slits here is moving in the negative so the equations become

Gap = A - B

Center = (A + B) / 2

 

Best Regards,

Abdalla.

 

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From: Pearson, Matthew <pearsonmr at ornl.gov>
Sent: Friday, January 5, 2024 5:52 PM
To: Torsten Bögershausen <Torsten.Bogershausen at ess.eu>; Abdalla Ahmad <Abdalla.Ahmad at sesame.org.jo>; tech-talk at aps.anl.gov <Tech-talk at aps.anl.gov>
Subject: RE: Behavior of the soft motor's DINP field

 

Hi,

 

Back to your problem:
There may be a timing problem of some kind,

between the poller towards the Galil and the soft “motor poller”.

 

It’s event driven, a CA monitor on the links defined by DINP, RDBL and RINP.

 

starts calculating and updates the soft motor RBV accordingly, but the soft motor stops before reaching the actual calculated position due to the fact that the DINP field receives 1 if both motors are done moving (DMOV = 1). For example it is supposed to reach 5 mm but it reaches to 4.97 for example.

 

I think the soft motor position will still update even though DINP=1. For example, if the encoder on an underlying real motor changes by itself (without a commanded move happening, with DMOV staying at 1) the soft motor position will still change.

·         I remembered that we are configuring our Galil controllers on a 8 ms update rate. I set the update rate to slower values and the issue can be resolved.

 

8ms update rate is fast. That’s polling the Galil controller at 125Hz. It may work, and I’ve tested close to 100Hz myself, but is it necessary for the application?

 

It also means both real motor records are being processed by the Galil driver at 125Hz, which means the transform and the soft motor record is being updated 2x that rate (250Hz).

 

Are you using UDP via the Galil driver? Perhaps the controller isn’t responding to every network request made by the Galil driver poller. Although, I’m not sure if that’s an issue here.

 

Cheers,

Matt

 

 

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