Re: motor record: soft motor & DMOV

[Kevin Peterson <kmpeters@anl.gov>]

On 8/28/13 12:26 AM, Mooney, Tim M. wrote:
> Also, DMOV is cleared in special(), before motion ever starts, so
> that there will be a guaranteed 1-0-1 transition of DMOV in response
> to a write to VAL - even if the write doesn't cause any motion (for
> example, because the new value isn't different enough from the old
> value).

This is a very important point that doesn't get enough attention.

When a soft motor is commanded to move, it is the motor record that
initially set the DMOV to zero; the value of DINP PV is ignored at this
point.  The first time the DINP PV is used is the first status update
after the move is initiated.  If the moving-poll rate of the real motors
is high, there can be a very narrow window during which the DINP calc
must be done.

In "soft motor record.db" the DINP field is set to
"$(PREFIX):doneMoving_". How is $(PREFIX):doneMoving_ calculated?

Kevin