records auto invalidation on timeout

[Matthieu Bec via Tech-talk <tech-talk at aps.anl.gov>]

Hello tech-talk,

LBT is using an EPICS db for alarming purpose. The db is a collection of soft records with the usual low/lsv, high/hsv, etc updated externally by programs doing CA puts.
I am trying to implement a scheme where no updates (for example the external program stopped running) auto invalidates those records.
Here's what my template looks like. It seems to work, but has a lot of plumbing.

Is there a simpler way to achieve this? either db or some deviceSupport I do not know?

Thank you,
Matthieu



# an input instance

record(ao, usr:input)
{
  field(DESC, "externally set via caput")
  field(HIHI, "10")
  field(HHSV, "MAJOR")
  field(LOW, "-1")
  field(LSV, "MINOR")
  field(PINI, "YES")
  field(VAL, "nan")
  field(FLNK, "usr:time")
}

record(ai, usr:time)
{
  field(DESC, "emulate .TIME that is private")
  field(DTYP, "Soft Timestamp")
  field(INP, "@%s")
  field(FLNK, "usr:value")
}

record(calc, "usr:value")
{
  field(DESC, "expires to nan,UDF,INVALID after 10s")
  field(INPA, "usr:input .MSS") # use .MSS (.MS gives LINK)
  field(INPB, "usr:time")
  field(INPC, "ioc:time")
  field(CALC, "(abs(B-C)<10)?A:nan")
  field(SCAN, "1 second")
}

# common stuff

record(ai, ioc:time)
{
  field(DESC, "ioc time")
  field(DTYP, "Soft Timestamp")
  field(INP, "@%s")
  field(SCAN, "1 second")
}