Re: How to work with motor record position counts larger than 2147483648?

[Torsten Bögershausen <torsten.bogershausen@esss.se>]

Thanks for the report.

There is even an older discussion here:
https://github.com/epics-modules/motor/issues/8


And the situation can be improved:
<https://github.com/EPICS-motor-wg/axis/commit/7a125b9c90298a111d20555e6e3794ae9e16fb21>

I am working on a "backport" to the motor module,
this will take some days.
/Torsten


On 23/01/18 00:02, Mark Rivers wrote:
> Hi Alex,
>
> The problem is that the RRBV field in the motor record is a 32-bit integer:
>
> This is from motorRecord.dbd:
>
>          field(RRBV,DBF_LONG) {
>
>                  prompt("Raw Readback Value")
>
>                  special(SPC_NOMOD)
>
>          }
>
> The motor driver reads back the theoretical and encoder positions as doubles, 
> but then they is converted to 32-bit integers in devMotorAsyn.c to be 
> compatible with the fields in the record.
>      if ( pPvt->needUpdate )
>
>      {
>
>          epicsInt32 rawvalue;
>
>          rawvalue = (epicsInt32)floor(pPvt->status.position + 0.5);
>
>          if (pmr->rmp != rawvalue)
>
>          {
>
>              pmr->rmp = rawvalue;
>
>              db_post_events(pmr, &pmr->rmp, DBE_VAL_LOG);
>
>          }
>
>          rawvalue = (epicsInt32)floor(pPvt->status.encoderPosition + 0.5);
>
>          if (pmr->rep != rawvalue)
>
>          {
>
>              pmr->rep = rawvalue;
>
>              db_post_events(pmr, &pmr->rep, DBE_VAL_LOG);
>
>          }
>
> Mark
>
> *From:* tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] 
> *On Behalf Of *Sobhani, Bayan
> *Sent:* Monday, January 22, 2018 4:20 PM
> *To:* tech-talk@aps.anl.gov
> *Subject:* How to work with motor record position counts larger than 2147483648?
>
> I am working on adapting the SmarAct MCS motor record driver for the MCS2, 
> which seems to record its position in picometers unlike the MCS’s nanometers.
> I have the following code in my polling function:
>
> Int64_t val = getp(0); //Gets position of channel 0 positioner
>
> printf(“%f\n”,(double) val); //prints -6000093133.000000
>
> setDoubleParam(c_p_->motorEncoderPosition_,(double)val);
>
> setDoubleParam(c_p_->motorPosition_,(double)val);
>
> …
>
> callParamCallbacks();
>
> return asynSuccess;
>
> But when I look at the motor record, the RRBV is shown as -2147483648. I looked 
> at asynMotorController.cpp and saw the line:
> createParam(motorEncoderPositionString,        asynParamFloat64,    
> &motorEncoderPosition_);
> Shouldn’t this mean I can write 64-bit floating point values to 
> motorEncoderPosition_ (i.e. larger than 2147483648)? How should I go about 
> working with position counts larger than 2147483648?
> Alex