Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> · Mon, 23 Mar 2020 16:37:19 +0000

Hi Hinko,

I'm not sure of the configuration.  Is this correct:

- Both $(P)$(R)TimestampIn and $(P)$(R)Timestamp are in the same IOC.  That is not the IOC you are killing.

- The TSEL link is talking to another IOC (the EVR IOC), PV="LAB-EVR-000:EvtECnt-I.TIME CP MS"

- Is the OUT link is talking to a local driver?  What does this driver do?  "@asyn($(PORT),$(ADDR=0),$(TIMEOUT=1))SIS8300.EVR.TIMESTAMP")

Does TimeStampIn record ever go into alarm state when the EVR IOC shuts down?  It may take the time that the OS requires to detect that a socket is closed, which can be many minutes.

It seems to me that the record that should first detect the problem is not using asyn, it is the TimestampIn record.  So this is really not an asyn question, it is the behavior of EPICS base in general for CP links.

Mark

________________________________
From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Hinko Kocevar via Tech-talk <tech-talk at aps.anl.gov>
Sent: Monday, March 23, 2020 11:11 AM
To: tech-talk at aps.anl.gov
Subject: detecting remote PV disconnect (asyn)

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