Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Thu, 21 Sep 2006 16:18:04 +0200

Hello Bernhard,
If you use the Alarm Handler (ALH) to display your alarms, there is a
configuration option that allows you to have an alarm appear only after
it occurred for a certain number of times or persisted for a certain time.

Look for chapter 6.3.12 or "Alarm Count Filter" in the Alarm Handler
User's Guide.
If you want to solve this within the database, use Pete's approach, but
rather use a calcout record and use the OCAL field (or a second calc
record) to write the RAWTEMP value to the final ai, else you will end up
showing the counter instead of the temperature.

I would separate the time counting from forwarding the value, which also
doesn't link the update period of your final TEMPERATURE ai to the time
counter resolution. So I would do something like
record (ai, "RAWTEMP")
{
	...
	field (SCAN, "I/O Intr")
	field (FLNK, "CALCFORWARD")
}
record (calc, "CALCFORWARD")
{
	field (CALC, "A")
	field (INPA, "RAWTEMP NPP MS")
	field (INPB, "CALCULATION NPP MS")
	field (FLNK, "TEMPERATURE")
}
record (calc, "CALCULATION")
{
	field (SCAN, "1 second")
	field (CALC, "(B>C||B<D)?(A+1):0")
	field (INPA, "CALCULATION.VAL")
	field (INPB, "RAWTEMP")
	field (INPC, "RAWTEMP.HIHI")
	field (INPD, "RAWTEMP.LOLO")
	field (HIHI, "60")
	field (HHSV, "MAJOR")
	field (FLNK, "CALCFORWARD")
}
record (ai, "TEMPERATURE")
{
	field (INP, "CALCFORWARD NPP MS")
}
(Code is not tested and may contain more bugs ...)
Hope this helps,
Ralph

Bernhard Lopez wrote:

Hi,
At our infrastructure monitoring system we have the case that
some temperature values should trigger an alarm only if they
remain above/below a threshold (HIHI/LOLO) for longer than a
defined amount of time.
As we could not find support for this feature in the documentation,
we would be glad to receive a suggestion regarding a solution or
implementation we could go for.
The involved sensor devices are represented by "ai" records
with a home-made device implementation. We use EPICS release
3.14 on Linux.
Many thanks in advance!
Bernhard.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System