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>]

Hi,

I think I found the cause of the problem.

ThetaM axis(motor) is Bragg angle of double crystal monochromator.

I created a pseudo motor Energy for it.

There is a conversion formula between ThetaM and Energy motors.

For calibration, in the formula there is an offset which can be modified by the endstation scientists.

Energy = formula(ThetaM + offset)

ThetaM = reversed_formula(Energy) - offset

And the offset has been set to 0.02.

So the value in the motor controller is indeed "the value in motor record - 0.02".

However, after ioc reboot, it's not always the case "-0.02", sometimes it's the original value.

Well, now the problem is how to solve/remedy this issue.

>My understanding is that the problem with the theta motor is that when you restart the IOC the motor position is different from where it was before the IOC shut down. 

As Mark said, that is the issue. Thank you.

>I can think of 3 reasons for this:
>    The position that you motorAxis::poll() function is reading before iocInit is indeed different.
>    The position has been set with motorAxis::setPosition()
>    Something has told the motor to actually move with motorAxis::move()

Very helpful suggestions indicating where I need to look at.

>Once back to work, could you add a monitor to the .DMOV and the .RCNT fields ?

I did more ioc reboot with monitoring DMOV and RCNT and in the middle set sleep time to 5.0.

It seemed nothing different from previous.

epicsThreadSleep(1.0)

$ camonitor DCM:ThetaM.VAL DCM:ThetaM.RBV DCM:ThetaM.DMOV DCM:ThetaM.RCNT
DCM:ThetaM.VAL             2025-01-03 10:00:33.506822 7.55376  
DCM:ThetaM.RBV             2025-01-03 10:00:33.506822 7.55381  
DCM:ThetaM.DMOV            2025-01-03 10:00:33.506822 1  
DCM:ThetaM.RCNT            2025-01-03 10:00:33.506822 2  

ioc reboot

CA.Client.Exception...............................................
    Warning: "Virtual circuit disconnect"
    Context: "172.16.1.1:40803"
    Source File: ../cac.cpp line 1215
DCM:ThetaM.VAL             2025-01-06 10:03:29.738414 *** disconnected
    Current Time: Mon Jan 06 2025 10:03:29.738356427
..................................................................
DCM:ThetaM.RBV             2025-01-06 10:03:29.738436 *** disconnected
DCM:ThetaM.DMOV            2025-01-06 10:03:29.738448 *** disconnected
DCM:ThetaM.RCNT            2025-01-06 10:03:29.738457 *** disconnected

DCM:ThetaM.VAL             2025-01-06 10:03:37.362640 7.55376    <-- ok
DCM:ThetaM.RBV             2025-01-06 10:03:37.362640 7.55376    <-- original VAL, not RBV
DCM:ThetaM.DMOV            2025-01-06 10:03:37.362640 1  
DCM:ThetaM.RCNT            2025-01-06 10:03:37.362640 0  

ioc reboot

CA.Client.Exception...............................................
    Warning: "Virtual circuit disconnect"
    Context: "172.16.1.1:45612"
    Source File: ../cac.cpp line 1215
    Current Time: Mon Jan 06 2025 10:07:58.862712293
DCM:ThetaM.VAL             2025-01-06 10:07:58.862746 *** disconnected
..................................................................
DCM:ThetaM.RBV             2025-01-06 10:07:58.862773 *** disconnected
DCM:ThetaM.DMOV            2025-01-06 10:07:58.862794 *** disconnected
DCM:ThetaM.RCNT            2025-01-06 10:07:58.862809 *** disconnected
DCM:ThetaM.VAL             2025-01-06 10:08:08.813621 7.53375    <-- -0.02
DCM:ThetaM.RBV             2025-01-06 10:08:08.813621 7.53371  
DCM:ThetaM.DMOV            2025-01-06 10:08:08.813621 0  
DCM:ThetaM.RCNT            2025-01-06 10:08:08.813621 2  
DCM:ThetaM.RCNT            2025-01-06 10:08:08.963770 3  
DCM:ThetaM.RBV             2025-01-06 10:08:09.113744 7.53376  
DCM:ThetaM.DMOV            2025-01-06 10:08:09.113744 1  
DCM:ThetaM.RBV             2025-01-06 10:08:09.284151 7.53381  

ioc reboot

CA.Client.Exception...............................................
DCM:ThetaM.VAL             2025-01-06 10:10:42.046330 *** disconnected
    Warning: "Virtual circuit disconnect"
    Context: "172.16.1.1:58118"
DCM:ThetaM.RBV             2025-01-06 10:10:42.046368 *** disconnected
    Source File: ../cac.cpp line 1215
    Current Time: Mon Jan 06 2025 10:10:42.046296206
DCM:ThetaM.DMOV            2025-01-06 10:10:42.046384 *** disconnected
..................................................................
DCM:ThetaM.RCNT            2025-01-06 10:10:42.046401 *** disconnected
DCM:ThetaM.VAL             2025-01-06 10:10:51.365415 7.51376    <-- -0.02
DCM:ThetaM.RBV             2025-01-06 10:10:51.365415 7.51351  
DCM:ThetaM.DMOV            2025-01-06 10:10:51.365415 0  
DCM:ThetaM.RCNT            2025-01-06 10:10:51.365415 0  
DCM:ThetaM.RBV             2025-01-06 10:10:51.685311 7.51356  
DCM:ThetaM.RBV             2025-01-06 10:10:52.015723 7.51376  
DCM:ThetaM.DMOV            2025-01-06 10:10:52.015723 1  


epicsThreadSleep(5.0)

ioc reboot


CA.Client.Exception...............................................
    Warning: "Virtual circuit disconnect"
    Context: "172.16.1.1:56451"
    Source File: ../cac.cpp line 1215
    Current Time: Mon Jan 06 2025 10:13:59.020537090
..................................................................
DCM:ThetaM.VAL             2025-01-06 10:13:59.020585 *** disconnected
DCM:ThetaM.RBV             2025-01-06 10:13:59.020614 *** disconnected
DCM:ThetaM.DMOV            2025-01-06 10:13:59.020631 *** disconnected
DCM:ThetaM.RCNT            2025-01-06 10:13:59.020647 *** disconnected
DCM:ThetaM.VAL             2025-01-06 10:14:13.087376 7.49377    <-- -0.02
DCM:ThetaM.RBV             2025-01-06 10:14:13.087376 7.49376  
DCM:ThetaM.DMOV            2025-01-06 10:14:13.087376 1  
DCM:ThetaM.RCNT            2025-01-06 10:14:13.087376 0 

On Sun, Jan 5, 2025 at 6:45 AM Mark Rivers <rivers at cars.uchicago.edu> wrote:

3 reasons!

 

From: Mark Rivers
Sent: Saturday, January 4, 2025 4:44 PM
To: LiangChih Chiang <yehnan174 at gmail.com>
Cc: Torsten Bögershausen <tboegi at edom.se>; 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.

 

• I turned them on before. There will be many messages; I don't know where to look at.

 

My understanding is that the problem with the theta motor is that when you restart the IOC the motor position is different from where it was before the IOC shut down.  I can think of 2 reasons for this:

 

• The position that you motorAxis::poll() function is reading before iocInit is indeed different.
• The position has been set with motorAxis::setPosition()
• Something has told the motor to actually move with motorAxis::move()

 

You should be able to add debugging to your motorAxis class in those functions to figure out what is happening.

 

Mark

 

 

From: LiangChih Chiang <yehnan174 at gmail.com>
Sent: Friday, January 3, 2025 7:41 PM
To: Mark Rivers <rivers at cars.uchicago.edu>
Cc: Torsten Bögershausen <tboegi at edom.se>; 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.

 

Hello, Mark,

 

>    Are these stepper motors or DC servos

stepper motors.

 

>    Do they have encoders?

Yes.

 

>Can you try temporarily removing the pseudo motor for energy, so there is only the real motor.  Does the problem exist?

I'll try after weekend.

 

>Before resorting to wireshark, I recommend just turning on ASYN_TRACE_ERROR, ASYN_TRACE_FLOW, and ASYN_TRACEIO_DRIVER in your startup script right after creating the driver.   

I'll try after weekend.

I turned them on before. There will be many messages; I don't know where to look at.

 

>That may help to understand what is happening.  

>You may also want to add additional asynPrint statements in your driver to see what it is doing.

I'll try after weekend.

But the question is that I don't know where in the code to add asynPrint.

 

 

I (we all) know it's extremely difficult to debug others' problems.

Any suggestions are appreciated.

 

Thanks for your helping and replying.

 

 

 

 

 

 

On Fri, Jan 3, 2025 at 10:25 PM Mark Rivers <rivers at cars.uchicago.edu> wrote:

I don't think you have told us:

 

• Are these stepper motors or DC servos

• Do they have encoders?

Can you try temporarily removing the pseudo motor for energy, so there is only the real motor.  Does the problem exist?

 

Before resorting to wireshark, I recommend just turning on ASYN_TRACE_ERROR, ASYN_TRACE_FLOW, and ASYN_TRACEIO_DRIVER in your startup script right after creating the driver.   That may help to understand what is happening.  You may also want to add additional asynPrint statements in your driver to see what it is doing.

 

Mark

 

 

---

From: LiangChih Chiang <yehnan174 at gmail.com>
Sent: Friday, January 3, 2025 3:35 AM
To: Torsten Bögershausen <tboegi at edom.se>
Cc: Mark Rivers <rivers at cars.uchicago.edu>; tech-talk at aps.anl.gov <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.

 

> What is special with DCM:Z1.V ?

Not special.

ThetaM axis is the most important.

>The polling, if it works for motor 1,2,3...,

>shouldn't it work for motor 0 as well ?

Yeah. That bothers me a lot.

 

>Did you mention that you are using a "soft motor" here ?

There is pseudo motor representing the energy of x-ray beam,

whose value is converted to and from ThetaM(Bragg angle).

>If not, it may be an idea to use wireshark to see what is

>going on between the EPICS IOC and the motion controller.

Well, by using wireshark, I don't know what parts or messages I need to see.

 

 

On Fri, Jan 3, 2025 at 4:20 PM Torsten Bögershausen <tboegi at edom.se> wrote:

Thinking about it:

What is special with DCM:Z1.V ?

The polling, if it works for motor 1,2,3...,
shouldn't it work for motor 0 as well ?

Did you mention that you are using a "soft motor" here ?

If not, it may be an idea to use wireshark to see what is
going on between the EPICS IOC and the motion controller.


On 2025-01-03 09:09, Torsten Bögershausen 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.
>>          >
>>
>