Experimental Physics and
Industrial Control System

"Kasemir, Kay" <[email protected]> · Thu, 14 Jan 2016 14:00:33 +0000

Hi:

> On Jan 13, 2016, at 5:53 PM, Lingyun Yang <[email protected]> wrote:
> Is there anyway skip updating any/some of the output PVs in the aSub routine ?

In general, EPICS records are for data-flow type of processing. They always process their outputs or forward links.

The one big exception is the calcout record where the OOPT field allows you to select if/when the output is written.
You can quite flexibly use the calcout record’s CALC field to compute _if_ you want to write an output, and then use the OCAL field to compute _what_ to write.

The scan-disable fields can also influence processing of records.
This is certainly a matter of preference, but personally I also prefer using the calcout record for such “process-if-..” type of logic because it’s more flexible.
Anything with DISA/DISV usually requires comments in the database to explain what you’re trying to do, while calcout record logic is more straight forward:

 # If input A goes above 5, write 13 to Some record
record(calcout, …
  field (CALC, “A>5”)
  field(OOPT, "Transition to Non-zero”)
  field(OCAL, “13”)
  field(OUT, “SomeRecord PP”)

Try expressing that with a bunch of CALC, AO records and DISA/DISV logic..

Thanks,
Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System