Re: [foxboro] Day of Week

Terry's remark is to the point. If you only need to do it once a week, it's
probably not so important.

But if it's really critical, use the station block parameters and a seven
day counter. Then devise a way to fire it off the first time on the right
day. Preloading the counter would take care of that. You can use a much
more complicated method of calculating the day of the week, but you won't
necessarily get a better result.

Jerry Hidahl
Process Control Engineer
Port Neches Performance Products
Huntsman Corporation


                                                                           
             "Doucet,                                                      
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And we also remember the Alex Johnson rules for programming IA.

But if the function is low criticality (print a report that can also be
done manually if the AW is down for a while), then the cron does in fact
work well and is less complex than CALC or IND. That is until you upgrade
your system.

Terry Doucet, Eng.

De : foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] De
la part de Jeremy Milum
Envoyé : June 9, 2009 9:42 AM
À : foxboro@xxxxxxxxxxxxx
Objet : Re: [foxboro] Day of Week

On Tue, Jun 9, 2009 at 8:24 AM, Jerry Hidahl<Jerry_Hidahl@xxxxxxxxxxxx>
wrote:
> I'm surprised no one has mentioned using the Unix cron tab or the Windows
> scheduled events from an AW/WP.  It's every bit as robust as running a
> sequence block to get the date from the same AW. And much simpler.

Both methods rely on the AW/WP being up at the exact instant you check
for the DOW, which is not something I would want to rely on, better to
run it in a CALC block which.



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