Experimental Physics and
Industrial Control System

Tim Mooney <[email protected]> · Wed, 29 Mar 2000 17:40:45 -0600 (CST)

re...

> I've run into a strange problem with a database.  In working with the scan
> record, I need to have Wait records that poke the PROC field in the scan
> record.
> 
> When I do so directly with OUTN in the Wait record, it works as expected.
> If I forward link the Wait record through some other records to a CalcOut,
> all the intermediate records process successfully, but the Scan record does
> not respond when the CalcOut processes.  If I point the OUT field of that
> CalcOut at somewhere else, it behaves properly, so the problem seems
> somehow due to the Scan record.
> 
> The only difference I can see is the the OUT link in the Wait record is a
> dynamic link, while the CalcOut has a standard CA link. 
> 
> Why do they behave differently ?

One possibility is that dynamic links are implemented with channel-access
calls, while standard links may be database links or channel-access links.
With database links, it's the link's job to decide whether or not processing
is to occur.  If you want to process a record with a link, the link attribute
must be PP.  (Exception: if the field you're writing to is inherently PP, then
the link attribute CA will also cause processing.)

Tim Mooney

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System