Experimental Physics and
Industrial Control System

 

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