Re: [foxboro] Timing changes on loaded CP40
- From: "Johnson, Alex P (IPS)" <alex.johnson@xxxxxxxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Sun, 11 Sep 2005 21:56:10 -0400
Actually, I was trying to say that the blocks DO NOT use the clock directly.
They count BPCs. So, skipped BPCs can have an impact on CALC block timers
(last longer), ACCUM block totals (read low), and PID block tuning.
Since the PID block is running less often than expected, the tuning should
be adjusted to match the change in execution frequency (or you should fix
the overruns).
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: Sunday, September 11, 2005 4:16 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Timing changes on loaded CP40
So Alex, are you saying that the PID algorithm timing should still be
correct since it's off some sort of scanning scheduler based on the
clock?
Regards
Adam
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx
<mailto:foxboro-bounce@xxxxxxxxxxxxx> ] On Behalf Of Johnson, Alex P
(IPS)
Sent: Monday, 12 September 2005 4:31 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Timing changes on loaded CP40
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
<outbind://4/www.invensys.com/usergroup2005>
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto: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 affect times. Of course it probably also
means the PID integral gains for the CP are also being affected
(admittedly only by around 17%).
Is this normal behaviour for a heavily loaded CP40?
Regards
Adam Pemberton
Coordinator Process Control
Lihir Management Company
Adam Pemberton
Coordinator Process Control
Lihir Management Company
Ph: +675 9865 655
Fax: +675 9865 666
Mob: Nogat
Postal:
Australia: GPO Box 905, Brisbane, QLD 4001
PNG: PO Box 789, Port Moresby, NCD
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