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<== Date ==> <== Thread ==>

Subject: Re: stale data monitor
From: "Bob Dalesio" <ldalesio@lanl.gov>
To: "Redman, Russell O." <Russell.Redman@nrc-cnrc.gc.ca>, "'Vladimir Sirotenko'" <sirotenko@fnal.gov>, tech-talk@aps.anl.gov
Date: Thu, 11 Sep 2003 07:23:37 -0600
Another option for handling this is:

Modify the driver to keep a count of the number of times the same value has been read. If the value is the same - some number of times - when the database comes to read the values - return an INVALID Status. It's a hardware failure that is being recognized here and as such, it is the responsibility of the driver. IMHO.

Bob



On Wed, 10 Sep 2003 13:58:59 -0700
"Redman, Russell O." <Russell.Redman@nrc-cnrc.gc.ca> wrote:
One possible way would be to construct a delay line of ai records, say
delay0, delay1 and delay2, and a calc record. Set their input links
delay0.INP = (hardware)
delay1.INP = delay0 NPP delay2.INP = delay1 NPP
calc.INPA = delay0 NPP
calc.INPB = delay1 NPP
calc.INPC = delay2 NPP
and their forward links delay0.FLNK = calc
delay1.FLNK = delay0
delay2.FLNK = delay1
Processing starts with delay2 which gets its new value from the current
value of delay1, then causes delay1 to process. Delay1 gets its new value
from the current value of delay0, then causes delay0 to process. Delay0
gets its new value from the hardware, then causes the calc record to process
and compare the three values. Initializing the chain might be a bit of a
chore, however. If you need to do this in more than one place, this purely EPICS solution is
not likely to be the best solution. It is a bit more of a fuss to
configure, but it would probably be easier in the long run to write a few
lines of C code to put into a subr or gensub record. Cheers,


Dr. Russell O. Redman
Tel: (250) 363-6917 | Fax: (250) 363-0045
< mailto:Russell.Redman@nrc-cnrc.gc.ca
<mailto:Russell.Redman@nrc-cnrc.gc.ca> >
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5071 West Saanich Road | 5071 West Saanich Road
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-----Original Message-----
From: Vladimir Sirotenko [mailto:sirotenko@fnal.gov]
Sent: Wednesday, 2003 September 10 12:24 PM
To: tech-talk@aps.anl.gov
Subject: stale data monitor


Hi,
Is there easy and natural way to monitor stale data from, say, ai record
just using EPICS records? For example, I have to send alarm when several
consecutive reading return the same value. The time interval for those
consecutive reading may be rather large, of the order of minutes. If it
would be shorter, I could use seq record with delays, but for several
minutes interval how can I trigger its processing?
Thanks,
Vladimir



Bob Dalesio ldalesio@lanl.gov 410 557 0297 Maryland 505 667 3414 Los Alamos 505 699 1632 Cell Phone 505 667 6087 Our Secretary (Lisa Marie)

References:
RE: stale data monitor Redman, Russell O.

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