RE: motor record/Aerotech Automation1

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

There may also be some amount of mechanical settling causing this.

 

Assuming the driver is correct (and not reading the controller position before reading the state, as Mark said), you can add in a non-zero motor record DLY to help with issues like this.

 

Cheers,

Matt

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Mark Rivers via Tech-talk
Sent: Monday, December 16, 2024 3:41 PM
To: Mark Rivers <rivers at cars.uchicago.edu>
Cc: Eric J. Edwards <ericjedwards at cornell.edu>; tech-talk at aps.anl.gov
Subject: [EXTERNAL] Re: motor record/Aerotech Automation1

 

Hi John,

 

Motor drivers usually have a “moving poll period” and an “idle poll period “. 

From your timestamps it looks like moving is 0.1 second and idle is 1 second. 

You might want to reduce the moving period to .02 or .01 second. 

 

The driver may be reporting the position before it reports the moving status in the poll function. 

Perhaps those should be swapped, so the final position is correct.

 

Mark

 

Sent from my iPhone

On Dec 16, 2024, at 2:29 PM, Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> wrote:

 Hi John,

 

Is this a DC motor with an encoder? 

If so, then the definition of “done” is a bit fuzzy, since the controller is constantly doing feedback to minimize the error. 

Controllers have different algorithms for deciding when a move is complete, e.g.

- The error is less than some threshold for a defined time period.

- The velocity is less than some threshold

- The theoretical move profile is complete.

 

In some cases these criteria can be adjusted by the user.

 

Mark

 

Sent from my iPhone

On Dec 16, 2024, at 2:18 PM, John Dobbins via Tech-talk <tech-talk at aps.anl.gov> wrote:



All,

 

I don't have a lot of experience with EPICS motors , so I don't know if this issue is specific to the motor record or the Aerotech Automation1 support.

[ Alma 9,  base-7.0.6, motor - current master, Automation1 - master from October ]

 

If I command a move, DMOV goes high before the move is complete.  Here is an example camonitor output for the motor RRBV and DMOV

 

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:02.376122 0  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:03.380158 2  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:04.384190 -1  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:05.389343 1  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:06.394224 3  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:07.398213 -1  

S5C1_DCM_BRG_MTR:m1.DMOV       2024-12-16 14:49:07.398213 0  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:07.754199 0  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:07.858188 17189  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:07.962166 105223  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:08.066075 263412  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:08.170173 441394  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:08.274134 622471  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:08.378163 776297  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:08.482268 854418  

S5C1_DCM_BRG_MTR:m1.DMOV       2024-12-16 14:49:08.482268 1  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:09.487278 874672  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:10.491359 874669  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:11.495310 874668  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:12.499206 874666  

S5C1_DCM_BRG_MTR:m1.RRBV       2024-12-16 14:49:13.503320 874668

 

One can see that DMOV has transitioned to one simultaneous with a position short of the final value.

 

What can I do about this?

 

Thanks,

 

John Dobbins

 

Research Support Specialist

Cornell High Energy Synchrotron Source

Cornell University

 

www.chess.cornell.edu