Re: get the timestamp of a record as a human-readable string and restore it after rebooting

["Mooney, Tim M. via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Yong,

Two things:

1. I think there might be a typo.  The calc _expression_ "1" doesn't do what you say you want the calcout record to do.
2. I don't see why you use PINI to process the stringin record, if you want it to have the timestamp of the last time recordA made a transition to 0.  If you remove the PINI setting, what is the value of the stringin record immediately after rebooting?

Tim Mooney (mooney at anl.gov) (630)252-5417
Beamline Controls Group (www.aps.anl.gov)
Advanced Photon Source, Argonne National Lab

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Hu, Yong via Tech-talk <tech-talk at aps.anl.gov>
Sent: Tuesday, August 18, 2020 6:00 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: get the timestamp of a record as a human-readable string and restore it after rebooting

 

Hello everyone,

 

Since the field .TIME is internal to a record (e.g. recordA), it seems not straightforward for a string record (e.g. recordB) to directly get the timestamp of recordA as a human-readable string, although it is straightforward for a Python program to put a record’s timestamp as a string.

 

I managed to use “Soft Timestamp” together with “TSEL” to get the timestamp of a not-on-the-same-IOC record as a human-readable string. See below:

record(calcout,"recordA -Calc_") {

   field(INPA,"recordA CP")

    field(CALC,"1")

    field(OOPT,"Transition To Zero")

    field(OUT, "recordB.PROC")

}

 

record(stringin, "recordB")

{

    field(DTYP,"Soft Timestamp")

field(PINI,"YES")

#without TSEL, recordB will not be exactly the same as recordA’s timestamp

    field(TSEL,"recordA.TIME")

    field(INP, "@%Y-%m-%d %H:%M:%S.%f")

    info(autosaveFields_pass0, "VAL")

}

 

recordA is a bi record running on another IOC (that is why I use CP in INPA). I want to use recordB to latch the timestamp of recordA when recordA’s value goes from 1 to 0. Everything seems working as expected. However, there is one problem with autosave. After the IOC is rebooted, the value of recordB is <undefined>, it is not restored to its saved value although I see the saved value “2020-08-15 01:18:55.236900451” in the *_pass0.sav file before I reboot the IOC. I also tried to use pass1, the same result <undefined>.

$ caget -a recordB

recordB     <undefined> <undefined>

 

I see some errors during the rebooting. I guess the reason why I get “dbGetTimeStamp failed” is that the CA link is not established yet before initial process (PINI=YES). However, when I look through the code https://github.com/epics-base/epics-base/blob/3.15/src/ioc/misc/iocInit.c, dbCaLinkInit() is indeed before initialProcess().

reboot_restore: entry for file 'settings_pass0.sav'

reboot_restore: Found filename 'settings_pass0.sav' in restoreFileList.

*** restoring from './as/save/settings_pass0.sav' at initHookState 6 (before record/device init) ***

reboot_restore: done with file 'settings_pass0.sav'

recGblGetTimeStamp: dbGetTimeStamp failed, recorddB.TSEL = recordA

 

How do I solve this problem? Any suggestions are appreciated!

I am using Base-3.15.6-2 and autosave-5.9 if versions matter.

 

Thanks,

Yong Hu