Experimental Physics and
Industrial Control System

Heinrich du Toit <[email protected]> · Fri, 02 Nov 2007 16:01:49 +0200

Hi
Thanks for all your help
Wonder why the FLNK isn't a direct DB link then if possible? (e.g.
record inside same IOC)

Does the fanout do it differently?
What would you say about the idea of just putting all the inputs on SCAN
= .2 second

and then all the calc(out) rule records also on .2seconds SCAN ?
The way I see it a calc record can then never work with a value older
than .4 seconds... which is fine for the system I think.
Can maybe just FLNK or fanout the critical stuff then
-H

Eric Norum wrote:

On Nov 2, 2007, at 8:30 AM, Ned Arnold wrote:

You may be able to eliminate the fanout records by careful design of
forward links and/or input link flags (PP, CP, etc).
For example, if the input record's forward link field referenced the
calc record and the calc record's forward link field referenced the
calcout record, all would process each time the input record
processed ... without a fanout.

Don't take this technique to extremes, though. I recall helping Steve
Shoaf diagnose problems with his database for a video switching
system. The database contained 128 records FLNK'd together. This
caused very weird IOC faults that we finally realized were caused by
stack overflow of the task processing the records -- 128 recursive
calls to the record processing routine forced the task stack pointer
past the end of the stack space.

--Eric Norum <[email protected]>

Advanced Photon Source

Argonne National Laboratory

(630) 252-4793

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System