Re: Get notified of alarms internally to IOC w/o requiring record fields

[David Bracey via Tech-talk <tech-talk@aps.anl.gov>]

Needed:

 

    auto dse = db_start_events(pctx, 0, 0, 0, epicsThreadPriorityCAServerLow);

 

 

From: David Bracey <dbracey@fnal.gov>
Date: Tuesday, November 25, 2025 at 9:06 AM
To: tech-talk@aps.anl.gov <tech-talk@aps.anl.gov>
Subject: Get notified of alarms internally to IOC w/o requiring record fields

I am messing around with some ideas, and I am trying to get notified of alarm states changing on PV’s without link fields or user events – basically without putting any requirements on PV’s or DB records.

 

I tried some code that intends to set a callback for the DBE_ALARM event, but I don’t seem to get called.  The code looks like this:

 

void my_event_func(void *user_arg, struct dbChannel *chan,

    int eventsRemaining, struct db_field_log *pfl)

{

    errlogPrintf("my_event_func\n");

}

 

int main(int argc,char *argv[])

{

    if(argc>=2) {

        iocsh(argv[1]);

        epicsThreadSleep(.2);

    }

 

    auto pctx = db_init_events();

    errlogPrintf("pctx %p\n", pctx);

 

    auto pchn = dbChannelCreate("SOME_");

    errlogPrintf("pchn %p %s\n", pchn, pchn ? pchn->name : "");

 

    auto psub = db_add_event(pctx, pchn, my_event_func, 0, DBE_ALARM);

    errlogPrintf("psub %p\n", psub);

 

    db_event_enable(psub);

 

    iocsh(NULL);

    epicsExit(0);

    return(0);

}

 

Does this seem feasible at all?

 

• Dave Bracey, Fermilab AD