Experimental Physics and
Industrial Control System

On Saturday 19 July 2014 10:45:39 Jameson Graef Rollins wrote:
> On Fri, Jul 18 2014, "Johnson, Andrew N." <[email protected]> wrote:
> > This seems to be a rather unusual case. It's easy to implement this
> > behavior using a calc record to do the equality comparison, but
> > equality is actually a fairly rare comparison to use for floating
> > point values (other than zero). If X is really an integer you could
> > use longin or longout records instead, you just have to set the LOW
> > and HIGH alarm levels to one either side of X and HYST to zero. If X
> > is not an integer and is read from an ADC say, you could calculate
> > the ADC values in engineering units adjacent to X and use them for
> > the LOW and HIGH fields of your ai/ao record. If X really is a
> > double value you could even calculate the next higher and lower
> > double values and use them, but you need an understanding of IEEE
> > floating point to do that properly.
> 
> Hi, Andrew.  Thanks so much for the response.
> 
> I imagine we are doing some a bit non-standard.  We use ai records for
> system parameters that need to take on non-integer values, such as
> digital gains.  As you suggest, we could calculate the next
> higher/lower double values and set the alarms to those, but that
> requires more intermediate work when setting the alarms.
> 
> It seems, though, that this case could be easily covered if either the
> HIGH or LOW alarm were changed to strictly greater/less than the
> alarm value.  Can you think of some reason this behavior would not be
> desired?

Why don't you just set DRVL=DRVH=<the desired value>. In that case the 
record simply can't take on any other value. No need to even think about 
alarms for situations that can never arise...

Cheers
Ben
-- 
"Make it so they have to reboot after every typo." ― Scott Adams

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Re: EPICS alarming on VAL != X Jameson Graef Rollins

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EPICS alarming on VAL != X Jameson Graef Rollins

Re: EPICS alarming on VAL != X Johnson, Andrew N.

Re: EPICS alarming on VAL != X Jameson Graef Rollins

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