Re: Undefined Timestamp on Motor Record

[Torsten Bögershausen via Tech-talk <tech-talk@aps.anl.gov>]

On 16/08/19 11:54, Dominic Oram - UKRI STFC wrote:
> Hi All,
>
> Thank you for all the suggestions.
>
> 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.
>
> 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?

Hej Dominic,
(And thanks for reporting this)
I needed to do some (unexpected) bug hunting.

Version A): The original motor R6-11 + the driver patched like this

     status = initialPollInternal();
     if (status != asynSuccess) {
       setIntegerParam(pC_->motorStatusCommsError_, 0);
       setIntegerParam(pC_->motorStatusCommsError_, 1);
     }
Will show:

IOC:m1                         2019-08-16 17:46:55.004182 0 COMM INVALID
IOC:m1.STAT                    2019-08-16 17:46:55.004182 COMM COMM INVALID
IOC:m1.SEVR                    2019-08-16 17:46:55.004182 INVALID COMM INVALID
IOC:m1.UDF                     2019-08-16 17:46:55.004182 0 COMM INVALID

Version B) The heavily patched motor here at ESS is able to produce a record 
status that is technically more correct:

IOC:m1                         <undefined> 0 UDF INVALID
IOC:m1.STAT                    <undefined> UDF UDF INVALID
IOC:m1.SEVR                    <undefined> INVALID UDF INVALID
IOC:m1.UDF                     <undefined> 1 UDF INVALID

---------
However, thinking about it,
I find the "COMM INVALID" more intuitive for a user then the "UDF INVALID".

What do others think ?

> 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