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

Subject: Re: Default value to field SCAN
From: Henrique Almeida <hdante.lnls@gmail.com>
To: Gabriel de Souza Fedel <gabriel.fedel@lnls.br>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Tue, 3 Jan 2017 09:31:35 -0300
 Gabriel, the default value for the SCAN field is zero, or "Passive":

https://github.com/epics-base/epics-base/blob/3.16/src/ioc/db/menuScan.dbd

 To change this default value, use either field(SCAN, "value") on the
record definition, or do a caput on the SCAN PV:

 record(abcd, xyz) {
   field(SCAN, ".1 second")
 }

 The message you are seeing is a symptom to some record or device
support problem. Note that all the necessary threads for all the scan
periods are always created:

https://github.com/epics-base/epics-base/blob/3.16/src/ioc/db/dbScan.c#L184

2017-01-03 8:57 GMT-03:00 Gabriel de Souza Fedel <gabriel.fedel@lnls.br>:
> Hi,
>
> When I create records and don't set the field SCAN, what is the default
> value? There is an way to change this?
>
> I'm having problems with a set of records without SCAN field that are
> consuming a lot of CPU, and receiving this messages:
>
> dbScan warning from '.2 second' scan thread:
>         Scan processing averages 0,00 seconds (0,00 .. 0,02).
>         Over-runs have now happened 283681 times in a row.
>         To fix this, move some records to a slower scan rate.
>
> dbScan warning from '.5 second' scan thread:
>         Scan processing averages 0,00 seconds (0,00 .. 0,03).
>         Over-runs have now happened 290049 times in a row.
>         To fix this, move some records to a slower scan rate.
>
> dbScan warning from '.1 second' scan thread:
>         Scan processing averages 0,00 seconds (0,00 .. 0,03).
>         Over-runs have now happened 278431 times in a row.
>         To fix this, move some records to a slower scan rate.
>
>
> If i remove small choices from dbd file (.1, .2 and .5 seconds) solves the
> problem. Apparently the records are being created with all SCAN
> values...some idea to solve this?
>
> Regards,
>
> --
> Gabriel Fedel
> Software de Operação das Linhas de Luz
> Laboratório Nacional de Luz Síncrotron – (LNLS)
> Centro Nacional de Pesquisa em Energia e Materiais (CNPEM)
> gabriel.fedel@lnls.br | +55 (19) 3512 1226
> www.lnls.cnpem.br


References:
Default value to field SCAN Gabriel de Souza Fedel

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