Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Tue, 01 Feb 2005 10:27:35 +0100

We have a few cases where HOPR/LOPR are set to the "reasonable" limits
to be used in regular operation, while DRVH/DRVL is set to the real
limits to avoid frying the hardware. That way the slider-dragging
operator stays within the green sector, while an expert can simply
right-click up the text input box and go to the limits without having to
use a different panel or channel. (I.e. operators can easily be
instructed to do this even during night-time calls.)
As far as I remember, the original idea was for HOPR/LOPR to be useful
limits for _graphical_ client (maybe not even mandatory), while the
DRVH/DRVL limits were intended to protect the hardware. The real-world
meaning might have shifted, though.
My experience is that any assumption about how a certain feature is used
will fail not even covering the existing cases (let alone ways someone
can think of). No matter how hard you try. Seems to be a general law.
Cheers,
Ralph.

Gavin Smith wrote:
Thanks Peter, Ralph and Allison.
I think I'll put in a feature request to the EDM system though. It
still seems to me that it is very counterintuitive for one EDM widget
to respect HOPR and LOPR, and one to ignore it.
Am I correct in thinking that the only time you might want to drive a
PV past HOPR/LOPRs is in debugging? After all, the HOPR and LOPR are
used to set the display limits, so you wouldn't be able to see a
larger change.
Gavin.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System