Experimental Physics and Industrial Control System
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Suggestion from the dark past: Can you just not give the people who you don't want to change the position a user interface that doesn't have the option?
(I remember somebody cringing at one of our user interfaces where you could change the setpoint of a temperature controller, which we sometimes used quite intentionally and that person saying wouldn't it be dangerous if that happened by accident (like somebody clicking the wrong button) and all I could reply to that was that it had never happened.)
Aloha, Maren Purves Head of Instrument and Telescope Software East Asian Observatory / JCMT
Hi Ray,
“motor.db” loads a bo record, “$(P)$(M)_able”, that the motor record’s SDIS field points to.
We use this to enable/disable the motor record. When disabled, writes to the motor record’s .VAL field are not allowed.
Kurt
Perhaps what you're looking for is simply to set the Motor Record low and high limits to the drive value you want to maintain.
You could also set the SPMG field to 0 or 'Stop'. That would allow someone to change the VAL field (which is what you said you wanted to not allow), but it will prevent the Motor from actually
moving until SMPG is changed back to 2 or 'Go'. Both of these use the exposed interface to the Motor Record, so in principle can be changed at any time. But they are also not uncommon things to do for motors that you want to not accidentally move.
Ray,
Can you provide more details about what "disabling the axis" means? The
behavior of the motor record's CNEN field, which is labeled "Torque" on
the motorx_all screen, is controller dependent; for some controllers
CNEN enables/disables drive power, for other controllers CNEN switches
between open and closed loop control, and some drivers do nothing when
CNEN is changed.
Kevin
On 10/2/23 12:32, Gregory, Ray via Tech-talk wrote:
> Hi,
>
> How can I prevent changing an EPICS motor record’s commanded position
> (.VAL field) without disabling the axis?
>
> Thank you,
>
> Ray
>
> Ray Gregory
>
> Oak Ridge National Laboratory
>
--
- References:
- preventing changing an EPICS motor's commanded position Gregory, Ray via Tech-talk
- Re: preventing changing an EPICS motor's commanded position Kevin Peterson via Tech-talk
- Re: preventing changing an EPICS motor's commanded position Matt Newville via Tech-talk
- RE: preventing changing an EPICS motor's commanded position Goetze, Kurt via Tech-talk
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ANJ, 03 Oct 2023 |
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