Experimental Physics and
Industrial Control System

Am 18.03.20 um 18:15 schrieb Ralph Lange via Core-talk:
> Oh, you're thinking "scalar to array" for this whole thing?
> I was always assuming "array to array".

Well, EPICS traditionally makes no distinction between arrays and
scalars: scalars are just arrays with one element. This is the case at
the level of record field definition and also in CA. (This is different
for pvData but we are talking about the IOC core which is still based on
the old type model.)

To answer your question, no, I did not *exclusively* think "scalar to
array". I merely used it as the simplest (and most convincing) example.
The argument is quite similar for "array to array":

  caput -a PV.[2:2:6] 3 1.0 2.0 3.0

has (IMHO) only one sensible interpretation namely "write 1.0 to PV[2],
2.0 to PV[4], and 3.0 to PV[6]".

Similarly,

record(wf,"X") {
  field(OUT,"PV.[2:2:6]")
}

should mean "write the first 3 elements of X.VAL to PV[2], pv[4], and
PV[6], respectively". If X.VAL has less elements (X.NORD < 3) then of
course only up to NORD elements are written.

The reason I make these assertions is that the "configuration" is
attached to the name of the target PV. IMO this makes it untuitively
clear that the target PV is what the configuration refers to, at least
by default.

Cheers
Ben

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

References:

Re: write to a single element of an array field Ben Franksen via Core-talk

Re: write to a single element of an array field Ralph Lange via Core-talk

Re: write to a single element of an array field Ben Franksen via Core-talk

Re: write to a single element of an array field Ralph Lange via Core-talk

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