Re: PV Access

[Ben Franksen via Tech-talk <tech-talk at aps.anl.gov>]

Am 26.03.20 um 07:09 schrieb Ralph Lange via Tech-talk:
>> # not working: error --> dbJLinkInit: Link type 'db' not found
>>
>> record(ai, "${SYS}:dbInput") {
>>
>>   field(INP, {db:"${SYS}:constFloatPi"})
>>
>> }
> The key is the second sentence in the documentation you refer to:
> The IOC continues to support the older link types that do not use JSON to
> specify their link addresses.

Hi Ralph,

I think your answer, while not exactly wrong, is a bit cryptic, so let
me explain.

The docs list the available link JSON types. There is no "db" link type
listed, which explains the error you get. What Ralph alluded to is the
reason /why/ there is no JSON "db" link type. This is because, strange
as it may sound, '{db:"${SYS}:constFloatPi"}' is actually a valid name
for a record and thus for a PV. A long, long time ago it was decided
that a PV name may contain any byte that is not reserved for a special
purpose by EPICS base (such as '.' and a few others), instead of a
priori limiting this set to something reasonable.

Cheers
Ben

________________________________

Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V.

Aufsichtsrat: Vorsitzender Dr. Volkmar Dietz, stv. Vorsitzende Dr. Jutta Koch-Unterseher
Geschäftsführung: Prof. Dr. Bernd Rech (Sprecher), Prof. Dr. Jan Lüning, Thomas Frederking

Sitz Berlin, AG Charlottenburg, 89 HRB 5583

Postadresse:
Hahn-Meitner-Platz 1
D-14109 Berlin

Attachment: pEpkey.asc
Description: application/pgp-keys