Re: I implemented the Model 3 of EPICS motor driver support, but the VAL and RBV of motor record are zero after IOC reboot.

[LiangChih Chiang via Tech-talk <tech-talk at aps.anl.gov>]

Thank you for replying. Happy New Year.

>a) The read back position of  "DCM:ThetaM.RBV" is flickering.
>   You see this already when the IOC is running.
>   Why is that ?

flickering?

The motor is pretty stable once moving is done.

For example:

DCM:ThetaM.VAL             2025-01-03 08:54:05.156115 7.51376   <-- different -0.02; set a new VAL
DCM:ThetaM.RBV             2025-01-03 08:54:05.156115 7.52741   <-- motor starts to move
DCM:ThetaM.RBV             2025-01-03 08:54:05.335235 7.52131  <-- moving...
DCM:ThetaM.RBV             2025-01-03 08:54:05.505113 7.51621  
DCM:ThetaM.RBV             2025-01-03 08:54:05.675255 7.51376  
DCM:ThetaM.RBV             2025-01-03 08:54:05.845205 7.51361  
DCM:ThetaM.VAL             2025-01-03 08:54:05.845205 7.51376  <-- motor record is down moving. RBV syncs back to VAL.
DCM:ThetaM.RBV             2025-01-03 08:54:05.995251 7.51356  <-- Well, the motor(axis) still moves a little bit due to inertia or other factors.
DCM:ThetaM.RBV             2025-01-03 08:54:06.495140 7.51371 
DCM:ThetaM.RBV             2025-01-03 08:54:06.795186 7.51376  
DCM:ThetaM.RBV             2025-01-03 08:54:06.965241 7.51381  <-- However, the movement is very small.

>   Mechanical load, high-precision encoder ?

motor resolution is 2.7778e-05 degree / pulse

encoder resolution is 5e-5 degree / count

>   Is the controller running in closed loop ?

No.

But its RTRY field of motor record is 10.

>   b1) Increase the sleep() even more, 5.0 seconds ??

I tried 3 and 8 seconds. No success.

I will try again after holidays.

>   b2) Use the patched version of the motor from ESS,
I'll take a look at it.

But it may not be feasible to change the underlying motor module.

On Fri, Jan 3, 2025 at 4:09 PM Torsten Bögershausen <tboegi at edom.se> wrote:

Hej again,
happy new year !
Thanks for reporting back and sharing your experiences.

I think that there are 2 problems/phenomenon :

a) The read back position of  "DCM:ThetaM.RBV" is flickering.
   You see this already when the IOC is running.
   Why is that ?
   Mechanics are suspected to be a contributer.
   Mechanical load, high-precision encoder ?
   Is the controller running in closed loop ?

b) The initialisation is still flaky - sometimes RBV has a value of 0.0
   I can see 3 ways to improve it:
   b1) Increase the sleep() even more, 5.0 seconds ??
   b2) Use the patched version of the motor from ESS,
       which has been improved to handle this.
       And comes with log-prints, which allow a better remote-debug
       using this log-prints
       https://github.com/EuropeanSpallationSource/motor
   b3) I have seen the use of an EPICS (?) hook somewhere in one
      of the motor-drivers. But after searching for hooks I still
      can not find an example here on my disk or in old emails.


Another question:
How much is the motor moving ?
/Torsten


On 2025-01-03 02:54, LiangChih Chiang wrote:
>
> I added epicsThreadSleep(1.0) after creating motor controller and axes.
>
> I use camonitor to trace the VAL/RBV of motor records of three axes.
> I rebooted ioc nine times.
> Please see the following log.
>
> I noticed that axes Z1 and Z2 successfully restored the VAL/RBV from the
> controller every time.
>
> But the behavior of axis ThetaM is strange.
> Two out of nine reboots, the VAL field of ThetaM record is successfully
> restored.
> One out of nine reboots, the VAL field of ThetaM record is set to zero.
> Six out of nine reboots, the VAL field of ThetaM record is set to
> (previous value - 0.02).
>
> Why -0.02?
>
>
> DCM:Z1.VAL                 2025-01-02 16:28:46.483683 -0.04
> DCM:Z1.RBV                 2025-01-02 16:28:46.483683 -0.0401
> DCM:Z2.VAL                 2025-01-02 20:41:47.713687 0.0657
> DCM:Z2.RBV                 2025-01-02 20:41:47.713687 0.0653
> DCM:ThetaM.VAL             2025-01-02 16:28:50.353358 7.53376  <--
> DCM:ThetaM.RBV             2025-01-02 16:28:50.353358 7.53376
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 08:46:20.410653 -0.0401
> DCM:Z1.RBV                 2025-01-03 08:46:20.410653 -0.04
> DCM:Z2.VAL                 2025-01-03 08:46:20.350513 0.0653
> DCM:Z2.RBV                 2025-01-03 08:46:20.350513 0.0657
> DCM:ThetaM.VAL             2025-01-03 08:46:20.500699 7.53376   <-- same
> as previous
> DCM:ThetaM.RBV             2025-01-03 08:46:20.500699 7.53376
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 08:54:04.045355 -0.04
> DCM:Z1.RBV                 2025-01-03 08:54:04.045355 -0.0401
> DCM:Z2.VAL                 2025-01-03 08:54:03.985246 0.0657
> DCM:Z2.RBV                 2025-01-03 08:54:03.985246 0.0653
> DCM:ThetaM.VAL             2025-01-03 08:54:05.156115 7.51376   <--
> different -0.02
> DCM:ThetaM.RBV             2025-01-03 08:54:05.156115 7.52741   <--
> motor move
> DCM:ThetaM.RBV             2025-01-03 08:54:05.335235 7.52131
> DCM:ThetaM.RBV             2025-01-03 08:54:05.505113 7.51621
> DCM:ThetaM.RBV             2025-01-03 08:54:05.675255 7.51376
> DCM:ThetaM.RBV             2025-01-03 08:54:05.845205 7.51361
> DCM:ThetaM.VAL             2025-01-03 08:54:05.845205 7.51376
> DCM:ThetaM.RBV             2025-01-03 08:54:05.995251 7.51356
> DCM:ThetaM.RBV             2025-01-03 08:54:06.495140 7.51371
> DCM:ThetaM.RBV             2025-01-03 08:54:06.795186 7.51376
> DCM:ThetaM.RBV             2025-01-03 08:54:06.965241 7.51381
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:00:47.829590 -0.0401
> DCM:Z1.RBV                 2025-01-03 09:00:47.829590 -0.04
> DCM:Z2.VAL                 2025-01-03 09:00:47.769508 0.0653
> DCM:Z2.RBV                 2025-01-03 09:00:47.769508 0.0657
> DCM:ThetaM.VAL             2025-01-03 09:00:49.279478 7.49377   <--
> different -0.01999
> DCM:ThetaM.RBV             2025-01-03 09:00:49.279478 7.49611   <--
> motor move
> DCM:ThetaM.RBV             2025-01-03 09:00:49.449660 7.49371
> DCM:ThetaM.RBV             2025-01-03 09:00:49.619596 7.49351
> DCM:ThetaM.VAL             2025-01-03 09:00:49.619596 7.49377
> DCM:ThetaM.RBV             2025-01-03 09:00:49.939543 7.49356
> DCM:ThetaM.RBV             2025-01-03 09:00:50.269661 7.49376
>
>
> Manually move ThetaM to 7.553761
>
> DCM:ThetaM.VAL             2025-01-03 09:04:05.044900 7.55378
> DCM:ThetaM.VAL             2025-01-03 09:04:05.045646 7.55376
> DCM:ThetaM.RBV             2025-01-03 09:04:05.371519 7.49566
> DCM:ThetaM.RBV             2025-01-03 09:04:05.541574 7.50071
> DCM:ThetaM.RBV             2025-01-03 09:04:05.711567 7.50711
> DCM:ThetaM.RBV             2025-01-03 09:04:05.881592 7.51536
> DCM:ThetaM.RBV             2025-01-03 09:04:06.061484 7.52551
> DCM:ThetaM.RBV             2025-01-03 09:04:06.231575 7.53506
> DCM:ThetaM.RBV             2025-01-03 09:04:06.402009 7.54296
> DCM:ThetaM.RBV             2025-01-03 09:04:06.571571 7.54866
> DCM:ThetaM.RBV             2025-01-03 09:04:06.741529 7.55221
> DCM:ThetaM.RBV             2025-01-03 09:04:06.911574 7.55296
> DCM:ThetaM.VAL             2025-01-03 09:04:06.911574 7.55376
> DCM:ThetaM.RBV             2025-01-03 09:04:07.071671 7.55301
> DCM:ThetaM.RBV             2025-01-03 09:04:07.241982 7.55326
> DCM:ThetaM.RBV             2025-01-03 09:04:07.561637 7.55381
> DCM:ThetaM.RBV             2025-01-03 09:04:07.881647 7.55346
> DCM:ThetaM.RBV             2025-01-03 09:04:08.211724 7.55356
> DCM:ThetaM.RBV             2025-01-03 09:04:08.531501 7.55376
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:05:56.102804 -0.04
> DCM:Z1.RBV                 2025-01-03 09:05:56.102804 -0.0401
> DCM:Z2.VAL                 2025-01-03 09:05:56.042681 0.0657
> DCM:Z2.RBV                 2025-01-03 09:05:56.042681 0.0653
> DCM:ThetaM.VAL             2025-01-03 09:05:56.174482 7.55376   <-- same
> as previous
> DCM:ThetaM.RBV             2025-01-03 09:05:56.174482 7.55376   <-- but
> motor move
> DCM:ThetaM.RBV             2025-01-03 09:05:57.012778 7.55206
> DCM:ThetaM.RBV             2025-01-03 09:05:57.502889 7.54196
> DCM:ThetaM.RBV             2025-01-03 09:05:57.822823 7.54366
> DCM:ThetaM.RBV             2025-01-03 09:05:57.992678 7.54791
> DCM:ThetaM.RBV             2025-01-03 09:05:58.162720 7.55171
> DCM:ThetaM.RBV             2025-01-03 09:05:58.342759 7.55266
> DCM:ThetaM.RBV             2025-01-03 09:05:58.492806 7.55271
> DCM:ThetaM.RBV             2025-01-03 09:05:58.662711 7.55371
> DCM:ThetaM.RBV             2025-01-03 09:05:58.962828 7.55376
> DCM:ThetaM.RBV             2025-01-03 09:05:59.132771 7.55381
> DCM:ThetaM.RBV             2025-01-03 09:06:02.762853 7.55386
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:09:37.385148 -0.0401
> DCM:Z1.RBV                 2025-01-03 09:09:37.385148 -0.04
> DCM:Z2.VAL                 2025-01-03 09:09:37.325204 0.0653
> DCM:Z2.RBV                 2025-01-03 09:09:37.325204 0.0657
> DCM:ThetaM.VAL             2025-01-03 09:09:38.354986 0         <--
> different, zero!
> DCM:ThetaM.RBV             2025-01-03 09:09:38.354986 7.55181   <--
> motor move
> DCM:ThetaM.RBV             2025-01-03 09:09:38.535008 7.54706
> DCM:ThetaM.RBV             2025-01-03 09:09:38.704917 7.54026
> DCM:ThetaM.RBV             2025-01-03 09:09:38.875048 7.53131
> DCM:ThetaM.RBV             2025-01-03 09:09:39.045385 7.52046
> DCM:ThetaM.RBV             2025-01-03 09:09:39.215134 7.50731
> DCM:ThetaM.RBV             2025-01-03 09:09:39.385166 7.49361
> DCM:ThetaM.RBV             2025-01-03 09:09:39.555112 7.48036
> DCM:ThetaM.RBV             2025-01-03 09:09:39.725153 7.46636
> DCM:ThetaM.RBV             2025-01-03 09:09:39.894942 7.45281
> DCM:ThetaM.RBV             2025-01-03 09:09:40.064989 7.43961
> DCM:ThetaM.RBV             2025-01-03 09:09:40.234971 7.42526
> DCM:ThetaM.RBV             2025-01-03 09:09:40.405113 7.41221
> DCM:ThetaM.RBV             2025-01-03 09:09:40.585072 7.39761
> DCM:ThetaM.RBV             2025-01-03 09:09:40.755044 7.38401
> DCM:ThetaM.RBV             2025-01-03 09:09:40.925113 7.37066
> DCM:ThetaM.RBV             2025-01-03 09:09:42.095077 7.31426
> DCM:ThetaM.VAL             2025-01-03 09:09:42.095077 7.31426  <-- I
> stop the motor.
> DCM:ThetaM.RBV             2025-01-03 09:09:46.705116 7.31421
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:12:18.906995 -0.04
> DCM:Z1.RBV                 2025-01-03 09:12:18.906995 -0.0401
> DCM:Z2.VAL                 2025-01-03 09:12:18.846984 0.0657
> DCM:Z2.RBV                 2025-01-03 09:12:18.846984 0.0653
> DCM:ThetaM.VAL             2025-01-03 09:12:21.346979 7.29431   <--
> different −0.01995
> DCM:ThetaM.RBV             2025-01-03 09:12:21.346979 7.29431   <--
> motor move
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:18:20.230656 -0.0401
> DCM:Z1.RBV                 2025-01-03 09:18:20.230656 -0.04
> DCM:Z2.VAL                 2025-01-03 09:18:20.170608 0.0653
> DCM:Z2.RBV                 2025-01-03 09:18:20.170608 0.0657
> DCM:ThetaM.VAL             2025-01-03 09:18:20.311337 7.27437   <--
> different −0.01994
> DCM:ThetaM.RBV             2025-01-03 09:18:20.311337 7.29431   <--
> motor move
> DCM:ThetaM.RBV             2025-01-03 09:18:21.150538 7.29231
> DCM:ThetaM.RBV             2025-01-03 09:18:21.320404 7.28771
> DCM:ThetaM.RBV             2025-01-03 09:18:21.500407 7.28171
> DCM:ThetaM.RBV             2025-01-03 09:18:21.670389 7.27681
> DCM:ThetaM.RBV             2025-01-03 09:18:21.840686 7.27421
> DCM:ThetaM.RBV             2025-01-03 09:18:22.010457 7.27406
> DCM:ThetaM.VAL             2025-01-03 09:18:22.010457 7.27437
> DCM:ThetaM.RBV             2025-01-03 09:18:22.330451 7.27421
> DCM:ThetaM.RBV             2025-01-03 09:18:22.660350 7.27431
> DCM:ThetaM.RBV             2025-01-03 09:18:22.960309 7.27436
> DCM:ThetaM.RBV             2025-01-03 09:18:23.130896 7.27441
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:22:00.722740 -0.04
> DCM:Z1.RBV                 2025-01-03 09:22:00.722740 -0.0401
> DCM:Z2.VAL                 2025-01-03 09:22:00.662695 0.0657
> DCM:Z2.RBV                 2025-01-03 09:22:00.662695 0.0653
> DCM:ThetaM.VAL             2025-01-03 09:22:02.912859 7.25442   <--
> different −0.01995
> DCM:ThetaM.RBV             2025-01-03 09:22:02.912859 7.25441   <--
> motor move
>
> ioc reboot
>
> DCM:Z1.VAL                 2025-01-03 09:33:58.400417 -0.0401
> DCM:Z1.RBV                 2025-01-03 09:33:58.400417 -0.04
> DCM:Z2.VAL                 2025-01-03 09:33:58.340350 0.0653
> DCM:Z2.RBV                 2025-01-03 09:33:58.340350 0.0657
> DCM:ThetaM.VAL             2025-01-03 09:33:59.330344 7.23447   <--
> different −0.01995
> DCM:ThetaM.RBV             2025-01-03 09:33:59.330344 7.25241   <--
> motor move
> DCM:ThetaM.RBV             2025-01-03 09:33:59.500272 7.24781
> DCM:ThetaM.RBV             2025-01-03 09:33:59.680584 7.24186
> DCM:ThetaM.RBV             2025-01-03 09:33:59.850291 7.23701
> DCM:ThetaM.RBV             2025-01-03 09:34:00.020355 7.23431
> DCM:ThetaM.RBV             2025-01-03 09:34:00.190267 7.23416
> DCM:ThetaM.VAL             2025-01-03 09:34:00.190267 7.23447
> DCM:ThetaM.RBV             2025-01-03 09:34:00.510337 7.23431
> DCM:ThetaM.RBV             2025-01-03 09:34:00.840415 7.23441
> DCM:ThetaM.RBV             2025-01-03 09:34:01.140389 7.23446
> DCM:ThetaM.RBV             2025-01-03 09:34:01.310255 7.23451
>
>
>
>
>
>
>
>
> On Thu, Jan 2, 2025 at 11:26 AM LiangChih Chiang <yehnan174 at gmail.com
> <mailto:yehnan174 at gmail.com>> wrote:
>
>     Hi,
>
>      >To explain a little more, it is important that the driver has
>     completed the first poll cycle for the position and status of each
>     axis before iocInit.
>      >This is because the motor record looks at those positions during
>     iocInit, and if there are non-zero it uses those values as the
>     current position.
>      >You can add the following to your startup script after you create
>     the controller and axes to sleep for 1 second.
>      >epicsThreadSleep(1.0)
>
>     I did add epicsThreadSleep(1.0).
>
>     There are 5 motors(axis 1 to 5) connected to the motor controller.
>
>     After epicsThreadSleep(1.0) added, it seems that the VAL/RBV of
>     motor records of axis 2 to 5 can be successfully loaded back from
>     the controller after IOC reboot.
>     But the behavior of axis 0 (this axis is the most important) is strange.
>
>     After IOC reboot, the motor record of axis 0 will move.
>     It seems that the VAL field is set to a new value
>     and I can't figure out the relationship between the new and old values.
>
>     The axis 0 is the main axis(Bragg angle) of a double crystal
>     monochromator,
>     and it has corresponding pseudo motor to represent the Energy of x-
>     ray beam.
>
>
>
>
>
>
>
>
>
>     On Wed, Nov 20, 2024 at 11:04 PM Mark Rivers
>     <rivers at cars.uchicago.edu <mailto:rivers at cars.uchicago.edu>> wrote:
>
>         To explain a little more, it is important that the driver has
>         completed the first poll cycle for the position and status of
>         each axis before iocInit.  This is because the motor record
>         looks at those positions during iocInit, and if there are non-
>         zero it uses those values as the current position.  You can add
>         the following to your startup script after you create the
>         controller and axes to sleep for 1 second.
>
>         epicsThreadSleep(1.0)
>
>         Let us know if this does not fix the problem.
>
>         Mark
>
>
>         ------------------------------------------------------------------------
>         *From:* Tech-talk <tech-talk-bounces at aps.anl.gov <mailto:tech-
>         talk-bounces at aps.anl.gov>> on behalf of Torsten Bögershausen via
>         Tech-talk <tech-talk at aps.anl.gov <mailto:tech-talk at aps.anl.gov>>
>         *Sent:* Wednesday, November 20, 2024 5:15 AM
>         *To:* LiangChih Chiang <yehnan174 at gmail.com
>         <mailto:yehnan174 at gmail.com>>; tech-talk at aps.anl.gov
>         <mailto:tech-talk at aps.anl.gov> <tech-talk at aps.anl.gov
>         <mailto:tech-talk at aps.anl.gov>>
>         *Subject:* Re: I implemented the Model 3 of EPICS motor driver
>         support, but the VAL and RBV of motor record are zero after IOC
>         reboot.
>         Hej,
>
>         without having seen ypur code, I would speculate that you run
>         into a not-unknown issue using Model 3 motors, connected via
>         a serial cable, USB or Ethernet?
>
>         The value that the motorRecord needs is read from the driver,
>         wich must have been able to read it from your hardware.
>         Here are ESS we have a patched motor, which can handle this.
>         If you use the upstream version, the easist workaround may be
>         to add a sleep() after the createController() line in your st.cmd
>
>         HTH
>         /Torsten
>
>
>         On 2024-11-20 09:47, LiangChih Chiang via Tech-talk wrote:
>          > Hello, EPICS mates.
>          >
>          > I implemented the Model 3 of EPICS motor driver support for
>         some motor
>          > controller,
>          > but the VAL and RBV of the motor record are zero after IOC
>         reboot.
>          >
>          > I think the motor record doesn't restore the values of motor
>         pulse and
>          > encoder count from the motor controller after IOC reboot.
>          >
>          > What member functions of asynMotorController and
>         asynMotorAxis classes
>          > should I implement?
>          >
>          >
>          > Best regards.
>          >
>