Experimental Physics and
Industrial Control System

Hinko Kocevar via Tech-talk <tech-talk at aps.anl.gov> · Mon, 23 Mar 2020 16:11:44 +0000

Hi,

I have an EVR PV that delivers timestamp to my asyn based DAQ IOC. I want to know if and when that PV is inaccessible - i.e. EVR IOC not running / died.

I have this DB construct:

# get timestamp from EVR event PV
# i.e. set TSEL: LAB-EVR-004:EvtECnt-I.TIME CP MS
record(stringin, "$(P)$(R)TimestampIn") {
    field(DTYP, "Soft Timestamp")
    # use dummy placeholder PV, change EVR prefix to a desired EVR IOC
    field(TSEL, "LAB-EVR-000:EvtECnt-I.TIME CP MS")
    field(INP,  "@%s.%f")
    field(FLNK, "$(P)$(R)Timestamp.PROC PP MS")
    info(autosaveFields, "TSEL")
}

# holds TS value in 'sec.nsec' format
record(stringout, "$(P)$(R)Timestamp")
{
    field(DOL,  "$(P)$(R)TimestampIn")
    field(OMSL, "closed_loop")
    field(DTYP, "asynOctetWrite")
    field(OUT,  "@asyn($(PORT),$(ADDR=0),$(TIMEOUT=1))SIS8300.EVR.TIMESTAMP")
}

Works as expected. The $(P)$(R)Timestamp is refreshed upon each update of the LAB-EVR-000:EvtECnt-I PV, feeding the value to the asyn based IOC code.

Upon killing the EVR IOC the $(P)$(R)TimestampIn and $(P)$(R)Timestamp show no apparent state change that the LAB-EVR-000:EvtECnt-I went away. At least looking that the "dbpr ... 4" output for the above mentioned PVs.

I was expecting the alarm fields to be set to something like "not connected". Is there a way, in asyn based IOC, to detect this situation?

Thanks,
Hinko

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System