Subroutine invoked only when PV limit exceeded?

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

Hello all,

 

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?

 

Thanks!

-Mark