RE: Subroutine invoked only when PV limit exceeded?

["Poff, Mark A" <mark.a.poff@boeing.com>]

Andrew, thanks very much for that suggestion.  I modified the sub record as follows and it seems to work:

record(“MY_PV_sub”)

{

field(SDIS, "MY_PV.SEVR")

field(DISV, "0")

field(INPA, “MY_PV”)

field(SNAM, “MY_PV_subroutine”)

}

 

This prevents the subroutine from being called when the Severity is zero - which is a significant improvement - but if the PV value bounces around while in the HIHI range (for example), the subroutine is called each time.  What I was hoping for is a setup which calls the subroutine only once when an alarm state is entered, and isn't called again until the alarm state is exited/re-entered.  For example, perhaps the subroutine, when called, could examine the current severity level and change the DISV value on the fly to a different severity level…but that might be a pretty ugly way to do it.  Do you have any thoughts?

 

Thanks again,

Mark

 

-----Original Message-----
From: Andrew Johnson [mailto:anj@aps.anl.gov]
Sent: Monday, July 28, 2014 12:14 PM
To: Poff, Mark A; tech-talk@aps.anl.gov
Subject: Re: Subroutine invoked only when PV limit exceeded?

 

Hi Mark,

 

On 07/28/2014 10:18 AM, Poff, Mark A wrote:

> In my EPICS database, for certain PVs I use forward links and sub

> records such that, whenever the PV value changes, a subroutine is

> called.  It’s a pretty basic implementation:

>

> record(longin, “MY_PV”)

> {

>     field(SCAN, “Passive”)

>     field(HIHI, “30”)

>     field(HHSV, “MAJOR”)

>     field(FLNK, “MY_PV_sub”)

> }

>

> record(“MY_PV_sub”)

> {

>     field(INPA, “MY_PV”)

>     field(SNAM, “MY_PV_subroutine”)

> }

>

> What I’d like to do additionally (or /_instead_/) is to call a

> subroutine only when MY_PV goes to the HIHI alarm state (in the

> example above, when the value of MY_PV goes from less than 30 to 30 or

> greater).  I assumed it could be done by somehow looking at

> MY_PV.SEVR, but I can’t figure out how to do it.  Is it possible to

> define the database records so that a subroutine is executed only when

> the associated PV goes into an alarm state?

 

You can use the SDIS link and DISV field of your MY_PV_sub record to do part of that, see https://wiki-ext.aps.anl.gov/epics/index.php/RRM_3-14_dbCommon#Scan_Fields

for a brief description, but you'll only be able to disable the subroutine on one of the alarm state/severity values (I might do that on MY_PV.SEVR == 0). However your subroutine can read the alarm status and severity through the existing INPA link and act accordingly. The code you need would look something like this:

 

#include "dbAccessDefs.h"

#include "menuAlarmStat.h"

 

long MY_PV_subroutine(subRecord *prec)

    epicsEnum16 stat, sevr;

 

    if (dbGetAlarm(&prec->inpa, &stat, &sevr)) {

        /* Handle link problem ... */

    }

    switch (stat) {

    case menuAlarmStatHIHI:

        /* ... */

        break;

    case menuAlarmStatHIGH:

        /* ... */

        break;

    }

    /* ... */

}

 

 

HTH,

 

- Andrew

--

Advertising may be described as the science of arresting the human intelligence long enough to get money from it. -- Stephen Leacock