Re: [foxboro] CP load thresh hold
- From: "Joseph M. Riccardi" <Joe@xxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Thu, 3 May 2012 09:02:19 -0400
Dirk,
On my last project we had major issues with overloaded FCP270s for a variety
of reasons. From memory there are 5 basic limits the FCP270s have (I think
Alex J. documented them in detail in an e-mail to this list about 8-10
months ago); memory, total number of blocks, number of blocks per second,
number of om lists, etc. As for Idle Time, I remember finding documentation
that recommended 10% or 20% (depending on which document I found) minimum
idle time. This 10%-20% minimum was required for standard overhead
functions, abnormal alarm handling (we had unique requirements for alarm
flooding), additional om lists (we had unique requirements for abnormal
display call ups in an emergency conditions), Sequence block loading is not
consistent, etc. We were in a difficult situation where we had to split
approximately 2 dozen FCP270s to retain the future expansion requirements
specified. However, under normal conditions, I follow guidelines similar to
what Kevin recommended below; 25% Idle Time...
It's not black or white so good luck...
Joseph M. Riccardi
386-441-0250 Office
386-451-7607 Cell
Joe@xxxxxxxxxxxxx
"To give real service you must add something that cannot be bought or
measured with money; and that is sincerity and integrity." - Donald A. Adams
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Kevin Fitzgerrell
Sent: Thursday, May 03, 2012 8:38 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] CP load thresh hold
For reasonably modern CPs including CP270s (both FCP and ZCP) I use 25%
idle time with no overruns as a guideline for fully loaded. At that point
I will still allow minor additions but no new project work. At 15% idle I
allow no new logic and actively plan to split or upgrade a CP. With the
block processing power in the CP60s and 270s I prefer to not to phase the
logic at all, at least not for loading reasons on 0.5 second BPC CPs.
On CPs with serial or Ethernet I/O or lots of traditional I/O you need to
watch I/O loading as well as block processing. Also need to pay attention
to OM loading.
Regards,
Kevin
On Thu, May 3, 2012 at 6:07 PM, Dirk Pauwels <dirk.pauwels@xxxxxxxxxx>wrote:
> List,
> What would be the thresh hold where you would consider a ZCP270 to be
> heavily loaded and where you would advise to either re - phase or enable a
> new CP or one that has a lower load?
>
> We usually look at the idle time load, which is more than 70% on all our
> CP's except for one, where it is below 70%
> We have no overruns on any of our CP's
>
>
> Ie:
>
> "BLOCK MEAN LOAD (BPLOAD)";"4"
> "CP MEAN LOAD (CPLOAD)";"44"
> "I/O MEAN LOAD (IOLOAD)";"30.2"
> "OM LOAD AVERAGE (OMLDAV)";"6.66667"
> "% OF SEQUENCE BLOCK LOAD (SQLOAD)";"15.4"
> "IDLE TIME (IDLETM)";"71.39"
>
> Rgds,
>
> Dirk
>
>
>
> _______________________________________________________________________
> This mailing list is neither sponsored nor endorsed by Invensys Process
> Systems (formerly The Foxboro Company). Use the info you obtain here at
> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
>
> foxboro mailing list: //www.freelists.org/list/foxboro
> to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
> to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave
>
>
_______________________________________________________________________
This mailing list is neither sponsored nor endorsed by Invensys Process
Systems (formerly The Foxboro Company). Use the info you obtain here at
your own risks. Read http://www.thecassandraproject.org/disclaimer.html
foxboro mailing list: //www.freelists.org/list/foxboro
to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave
_______________________________________________________________________
This mailing list is neither sponsored nor endorsed by Invensys Process
Systems (formerly The Foxboro Company). Use the info you obtain here at
your own risks. Read http://www.thecassandraproject.org/disclaimer.html
foxboro mailing list: //www.freelists.org/list/foxboro
to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave
Other related posts:
