Experimental Physics and
Industrial Control System

Emma Shepherd <[email protected]> · Wed, 29 May 2013 08:27:34 +1000

Hi Ron,

> On the other hand, all of the above may be off base and what you are
> asking for (as Tim alluded to) is to have RDBD ignored on the initial
> move (on a change in VAL/DVAL/RVAL). In other words, RDBD only applies
> to retries.

Yes, that's what I meant!  I just want to be able to demand moves that are smaller than .RDBD (but they will still be >= MRES).

Cheers,
Emma

> -----Original Message-----
> From: Ron Sluiter [mailto:[email protected]]
> Sent: Wednesday, 29 May 2013 1:48 AM
> To: Emma Shepherd
> Cc: [email protected]
> Subject: Re: Motor record .RDBD field
>
> Hello Emma,
>
> On 5/27/2013 5:57 PM, Emma Shepherd wrote:
> > The .RDBD field of the motor record limits the smallest allowed move
> I would describe this slightly differently...
> The motor resolution field (MRES) defines the smallest allowed move.
> The motor record limits the retry deadband (RDBD) to be >= motor
> resolution (MRES).
> This prevents the record from attempting to do retry moves that are
> smaller than MRES.
>
> >   - quite often we want to set this very low so that we can do small
> step moves.
>
> By "this", I presume you are referring to the retry deadband (RDBD) and
> that you want to set RDBD less than the motor resolution.
>
> How does the Delta Tau handle a relative move that is less than MRES?
>
> The only motor controller I have investigated for this scenario (i.e.,
> relative moves < MRES) is the OMS VME58.
> Rather than accumulating "too small" relative moves, the OMS VME58
> ignores them.
> For example, if I set MRES=0.1, Max retry count (RTRY)  = 100 and the
> position error at the end of a move is 0.09, the OMS VME58 will be
> command to do 100 retries, but nothing moves (I am referring here to a
> hypothetical motor record where RDBD is not limited by MRES).
>
> > It would be better if we could somehow decouple the use of .RDBD in
> the retry sense from the smallest allowed move.
>
> On the other hand, all of the above may be off base and what you are
> asking for (as Tim alluded to) is to have RDBD ignored on the initial
> move (on a change in VAL/DVAL/RVAL). In other words, RDBD only applies
> to retries.
>
> Which is it?
>
> Ron

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System