Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Fri, 02 Nov 2007 19:46:04 +0100

Hello Heinrich,
If you additionally set the PHAS field of all input records to a low
number (e.g. 1) and the PHAS field of all calc records to a higher
number (e.g. 2), you will ensure that the .2sec-task will first process
all inputs and then process all calcs.
That way your calcs will always see all input values from the same run
of the .2sec-task, so they will always be newer than (0.2 seconds plus
run time of .2-sec-processing).
Possible exceptions:

Asynchronously processing inputs: calcs see the old value.

Overloading the 0.2sec-task (processing all .2sec- records takes longer
than .2 sec): major screw up.
Difference to FLNKs: FLNKs ensure that each pointed-to calc record is
processed directly and immediately after the FLNKing input record,
setting the PHAS field to (1,2) only ensures that all calc records (in
any order) are processed after all the input records (in any order).
Ralph

Heinrich du Toit wrote:

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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System