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<== Date ==> <== Thread ==>

Subject: RE: Undefined Timestamp on Motor Record
From: "Pearson, Matthew R. via Tech-talk" <tech-talk@aps.anl.gov>
To: Dominic Oram - UKRI STFC <dominic.oram@stfc.ac.uk>, Torsten Bögershausen <torsten.bogershausen@esss.se>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Fri, 16 Aug 2019 18:21:42 +0000
Hi,
 
> Writing to the PROC field after iocInit or setting PINI to 1 both fix the issue. As
> does setting motorStatusCommsError_ to 0 first then to 1. So I will do one of
> these.
> 

Take care with processing the motor record after IOC init. It could easily cause the motor to move if the motor record has a position different from what's currently on the controller.

Cheers,
Matt

> Torsten, the initial state I see isn't actually a conventional UDF state. The UDF
> field is 0 and there are no alarms on the PV. The only way of telling that it's in
> this state is that the timestamp is invalid. If it was a normal UDF state I would
> be happy just leaving it as the alarms will propagate through to the user. In
> the timestamp invalid state it's not obvious that there is an error. Are you
> instead seeing a normal UDF state?
> 
> Thanks,
> Dominic
> 
> -----Original Message-----
> From: Torsten Bögershausen <torsten.bogershausen@esss.se>
> Sent: 16 August 2019 07:45
> To: Oram, Dominic (STFC,RAL,ISIS) <dominic.oram@stfc.ac.uk>; tech-
> talk@aps.anl.gov
> Subject: Re: Undefined Timestamp on Motor Record
> 
> 
> 
> On 15/08/19 19:16, Dominic Oram - UKRI STFC via Tech-talk wrote:
> > Hello,
> >
> > I'm in the process of writing a model 3 motor driver using version 6-11 of
> the motor record.
> >
> > I have found some unexpected behaviour on initialisation if the driver has
> no device connected.
> >
> > It appears the motor stays in the following state unless a parameter is
> updated at some point after initialisation (I'm not sure when):
> >
> > caget -a MOTOR
> > MOTOR        <undefined> 0
> >
> > If I have no device connected I set motorStatusCommsError_ to 1 on the
> first call to poll(). However, because all subsequent calls to poll() do not
> change any parameters I stay in the above state. I would instead expect to
> see something like:
> >
> > caget -a MOTOR
> > MOTOR        2019-08-15 15:57:41.931650 0 COMM INVALID
> >
> > as in the undefined timestamp situation it's not obvious to users that there
> is a comm error.
> >
> > Setting motorStatusCommsError_ to 1 at some time after initialisation does
> give me the expected state.
> >
> > Is this actually expected behaviour?
> May be, may be not.
> My understanding is, that all EPICS records stay in "undefined" state (UDF)
> until the device support is able to talk to the device.
> In that sense the "undefined" state is OK.
> (And this is what we do with motors here at ESS,
>   never connected -> undefined.)
> 
>  > Do other people see something similar?
> Yes, fully reproducible here.
> I think that easiest solution is to do a workaround like this:
> 
>    status = initialPollInternal();
>    if (status != asynSuccess) {
>      setIntegerParam(pC_->motorStatusCommsError_, 0);
>      setIntegerParam(pC_->motorStatusCommsError_, 1);
>    }
> 
> >
> > Thanks,
> >
> > Dominic Oram
> > Senior Software Engineer
> > Experimental Controls
> > ISIS Neutron and Muon Source
> >

References:
Undefined Timestamp on Motor Record Dominic Oram - UKRI STFC via Tech-talk
Re: Undefined Timestamp on Motor Record Torsten Bögershausen via Tech-talk
RE: Undefined Timestamp on Motor Record Dominic Oram - UKRI STFC via Tech-talk

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