Re: [foxboro] Timing changes on loaded CP40
- From: "Johnson, Alex P (IPS)" <alex.johnson@xxxxxxxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Sun, 11 Sep 2005 14:30:38 -0400
The blocks don't actually use elapsed time for their calculations, they use
a BPC counter.
For that reason, you see the observed behavior on things like ACCUM block
and CALC block in heavily loaded Control Stations.
Regards,
Alex Johnson
Invensys Systems, Inc.
10707 Haddington
Houston, TX 77063
+1 713 722 2859 (voice)
+1 713 932 0222 (fax)
+1 713 722 2700 (switchboard)
alex.johnson@xxxxxxxxxxxxxxxx
I hope to see you at the Invensys Process System User Group meeting October
3-6 in Houston, TX -
www.invensys.com/usergroup2005
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Adam.Pemberton@xxxxxxxxxxxx
Sent: Thursday, September 08, 2005 4:54 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] Timing changes on loaded CP40
I have recently discovered that the timer for the OSP instruction of a
LOGIC block that is configured to run at 60 seconds continuously is
running at around 72 seconds. The relevant instructions are:
CST
IN ~BO02
OSP 60
OUT BO02
which is meant to generate a low pulse for one scan very 60 seconds.
The CP is heavily loaded (~1.5 overruns/sec, 973328 total memory free)
but I would not expect it to effect times. Of course it probably also
means the PID integral gains for the CP are also being effected
(admitedly only by around 17%).
Is this normal behaviour for a heavily loaded CP40?
Regards
Adam Pemberton
Coordinator Process Control
Lihir Management Company
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