Experimental Physics and
Industrial Control System

Érico Nogueira Rolim via Tech-talk <tech-talk at aps.anl.gov> · Thu, 23 Mar 2023 20:17:50 +0000

Hello!

I am using Constant Link Values, as documented in [1], to initialize
some waveforms in my IOC. I'm defining my records as shown below:

record(waveform, "Array-Cte"){
     field(FTVL, "LONG")
     field(NELM, "4")
     field(INP, [1,2,3,4])
}

However, when I use camonitor or pvget to receive their values, I am
notified that their values are, in fact, undefined/invalid:

$ pvget Array-Cte

Array-Cte  <undefined>              INVALID DRIVER UDF [1,2,3,4]

$ camonitor Array-Cte

Array-Cte <undefined> 4 1 2 3 4 UDF INVALID

If I add field(PINI, YES) to the record definition, I no longer get
notified about invalid values or anything. But it feels wrong to have to
add PINI in this case, since I'm declaring an initializer explicitly,
and it also feels ugly to leave the UDF/INVALID text in the output. Is
this expected behavior?

I am using epics-7 at the tip of master as of today
(5eff3803a83fbc3ea855b63841f5359c09830ade). This happens for waveforms
where FTVL is "STRING" as well, at the very least. It also happens if I
use the "{const: [1,2,3,4]}" syntax from [2].

[1] https://epics.anl.gov/base/R3-16/1-docs/RELEASE_NOTES.html

[2] https://epics.anl.gov/base/R7-0/7-docs/links.html

Thank you,

Érico

P.S.: I couldn't find documentation that specified clearly that JSON
links could be used in places like input links for "newer" EPICS
releases, outside of the release notes. That might be an interesting
hole to plug in the docs. Would it go somewhere like [3]? I could try to
tackle it.

[3]
https://docs.epics-controls.org/en/latest/guides/EPICS_Process_Database_Concepts.html

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System