Hi Torsten,
The deferred moves logic is really associated with a controller concept rather than an axis, so it can’t be entirely handled by the motor record. For example, a lot of controllers provide the ability to synchronize a multi-axis move start
(and sometimes even a start and stop time), and that needs a command sequence something like:
Axis 1: set new position
Axis 2: set new position
Axis 3: set new position
Axes 1,2,3: start moving (in one command) <- a single motor record can’t do this
It’s possible some of the logic could be handled in the controller and axis base class poll functions. Although most (or all) drivers override those and don’t call the base class function since they currently don’t do anything.
Cheers,
Matt
From: Torsten Bögershausen <Torsten.Bogershausen at ess.eu>
Sent: Friday, March 10, 2023 12:04 PM
To: Pearson, Matthew <pearsonmr at ornl.gov>; Laurenz Rettig <rettig at fhi-berlin.mpg.de>; tech-talk at aps.anl.gov
Subject: Re: [EXTERNAL] DeferredMoves without setting moving flag
Oh, I was to fast with my first response.
The line you wrote, Matt, could go into the generic code, right ?
/Torsten
Hi,
Certainly that behavior can be confusing. We enable deferred moves, set the position, and a motor appears to be moving before we say ‘Go’. However, I think it is necessary so that the motor record
doesn’t think the move is completed before we have started moving. If you are relying on a callback or forward links or looking for a DMOV 0->1 transition, you’ll be depending on this behavior.
Also that line in asynMotorController.cpp applies to all kinds of moves and not just deferred moves. This is necessary for the same reasons, to prevent the motor record thinking that the move is
complete before it’s even started and the polling function has chance to return the correct moving status. It’s likely almost every Asyn motor driver depends on that line in the base class writeFloat64 function.
In the poll() function in your derived class, it’s usually handled by looking at the deferred move flag for an axis. If deferred moves is enabled, then the poller reports motorStatusDone=0, something
like:
if (deferred_move) {
moving = true;
} else {
//calculate moving flag as normal
}
Cheers,
Matt
Hi,
I've been working on an asyn motor controller with DeferredMoves. This in principle works, however I noticed that when DeferedMoves is enabled, and I change the setpoint of an axis, the moving flag is raised for
a short time (i.e. DMOV=0), even though the axis is not moving yet. I would like to get rid of this behavior.
As far as I understand it, this is probably induced by the calls to "pAxis->setIntegerParam(motorStatusDone_,
0);" here:
https://github.com/epics-modules/motor/blob/34474ed958838ea5083f598fa4bd9f1ca7e1821c/motorApp/MotorSrc/asynMotorController.cpp#L317
and the flag is reset by the next call of the axis poll() function.
Is there a simple way to avoid this, or do I have to rewrite the whole
writeFloat64 function in my controller driver, and remove these lines?
Thanks,
Laurenz
--
Dr. Laurenz Rettig rettig at fhi-berlin.mpg.de
Emmy Noether Research Group Dynamics of Correlated Materials
Fritz Haber Institute of the Max Planck Society
Department of Physical Chemistry
Faradayweg 4-6 Tel: +49 30 8413 5225
14195 Berlin, Germany Fax: +49 30 8413-5387